Chevy 4.8L, 5.3L or 6.0L Intake Manifold Assembly, Replaces GM OEM # 17113697

1999-2002 GM Full-Size Vehicles with the  4.8L, 5.3L or 6.0L  engines with the EGR Tube option.

GM OEM Intake Manifold part number 17113697


This part fits 85 GM vehicles with various  options, below is a overview of  the intake manifolds fitment.
Here is a link to specific Year/Make/Model with 8th digit Vin check.

GM has two designs of  fuel systems, returned or return-less.  The difference is in the fuel pressure regulator, either mounted on the fuel rail or on top of the fuel pump.

The most common fuel system is the returned style. If installing this intake manifold on a return-less system, there is no modification of the vacuum routing necessary.

Adding the vacuum source for the fuel pressure regulator can be done two ways.
You could add a tee fitting into the PCV hose.  Or on most models, there is a  un-used vacuum port on the passenger side of the intake. is now offering the GM Intake Manifold 17113697  that has been modified to work with vehicles that have an EGR tube feature

Installing a Fuel Pump with a New Harness Connector on a 1999-2003 Chevrolet or GMC Truck?

On many GM applications, the wiring harness that connects to the fuel pump assembly is not properly inspected as part of fuel system repair.  This harness is prone to failure, leading to misdiagnosis and vehicle come-backs. Connector housing cracks, pin and contact looseness, and wire crimp issues can cause symptoms that simulate an issue with the fuel pump. It is recommended that the wiring connector be replaced with the pump to avoid unnecessary problems.

* Tech Note- When replacing the fuel pump harness connector be sure to remove as much of the old wiring as possible. For example, if the connector had a poor connection this would create a resistance problem resulting in heat. This excessive heat melts the wiring insulation allowing moisture to enter and corrode the wiring, resulting in future problems.

ACDelco MU1613/19104406 Fuel Pump Module & Sender Assembly/Sending Unit
Replaces These Part #’s: 19153711, P74835M, 25345026, 19121626, MU1516, MU1089, 25162874

How to identifying the Fuel pump wiring harness connector on 1999-2003 Chevrolet Silverado and GMC Sierra Trucks. First look at the new pig-tail connector, you can separate these 4 wires into two circuits by the gauge (diameter or thickness) of the wire, two wires will be bigger gauge  than the other two.  The thicker gauge wires are for the pump to handle the higher voltage drawl.  The smaller gauge wires are for the level sensor, a low voltage circuit.

Wiring color does vary from model to model, but with noting the wire diameter this is easy to work through.  Working with the larger two diameter wires first, the black wire (Pump Ground) will match to another large diameter black wire. The 12 volt pump feed wire will be most-likely gray but, is not unusual to see a white wire here (Just be sure of the gauge diameter).

Now working with the two smaller gauge wires for the fuel level sensor. The level sensor signal wire is purple and sometimes with a white tracer stripe, this will match up with the connector purple wire. For the level sensor reference wire, the orange/black wire (on the supplied connector) this will connect to the smaller black wire on the vehicle harness. *NOTE- On very early models this small black ground wire may not there, no problem,  just connect this wire to the other ground (the large diameter black wire).

Blower motor not working on all fan speeds? How to replace the blower motor resistor on a Chevrolet Silverado

Losing fan speed settings, is the most common complaint of a bad blower resistor.
On this 2001 Chevrolet Silverado  the customer has lost fan speeds 1 and 2.

Also check out’s Youtube Channel for this Repair

These Parts can be found at, Click here.

On the 1999-2007 General Motor Truck Series the blower resistor is located near the blower motor, under the glove box.  To gain access to the blower resistor you have to remove a cover box, held on by two 7mm bolts.

On this vehicle the customer has a aftermarket floor mat making it difficult to remove cover, so we will work around it. Normally this cover would be removed.  The blower resistor is mounted by two 5.5mm bolts, with two wiring connectors.

One is a 2-wire pigtail coming off the resistor going to the blower motor. This one is hard to reach, use a small screw driver to release the connector tab.  The other is a 7-wire connector from the A/C control head. This connector should be inspected for damage, it is very common to find a melted connection here that would require the pigtail connector to be replaced also.

To install, first connect the wiring.  But, before completing the reassembly, test the system for correct fan speed operation.

*Tech Tip- If your finding yourself replacing the blower resistor for the second time, most-likely the blower motor is a fault. As the blower motor wears, it is very common for the motor to demand more amperage.  This demand of more amps often is too much for the resistor, causing the resistor to fail prematurely. Check for the Blower Motor for Your Vehicle.

Dual Temperature Control, Automatic Temperature Control (ATC) or also called Electronic Climate Control not working correctly. Mode selection not working or the lose of the ability to switch airflow, which defaults to the defrost setting.

Today’s Vehicle Electronics are becoming very High-tech with the addition of many new creature comforts. One such feature is Dual Temperature Control, Automatic Temperature Control (ATC) or also called Electronic Climate Control. This feature allows the ability of adjusting different temperatures and fan speeds for the driver and passengers. Another word associated with temperature controls is  HVAC (heating, ventilation, and air conditioning) which refers to technology of indoor or automotive environmental comfort. Most common failure complaints with ATC systems is the mode selection fails or loses it’s ability to switch airflow which defaults to the defrost setting. This system is very complex, with a specified procedure to determine the particular conditions present. This should be diagnosed by a Certified Automotive Technician and requires the use of a scan tool to check for set DTC’s which may affect HVAC operations when present.

Dorman Products now offers a line of remanufatured Climate Control Modules. Dorman has recognized a few failures and improved these problems of the climate control modules.
With all modules one failure that was redesigned is in the mode selection, which results in the lose of ability to switch airflow and defaults to the defrost setting.
On models 599-030, 599-001 and 599-003 the lamp failures have be addressed.
Model 599-030 a revise to the back-lighting has been done along with a update to the deterioration of o-rings. These Remanufactured climate control modules are fully tested, and are plug and play ready for easy installation with No Programming Required.


General Motors 2005-2007
Manual Dual Temperature Control
Avalanche 1500/2500, Escalade, Suburban, Tahoe, Yukon, Silverado/Sierra 1500/2500HD/3500

599-001– w/Rear Defrost OEM Direct Cross #’s 10370034, 15832315, 21997353

599-003– w/o Rear Defrost OEM Direct Cross #’s 10370033, 15832313, 21997351

General Motors 2005-2006
Auto Dual Temperature Control
Avalanche, Escalade, Sierra,
Silverado 2007-05, Suburban, Tahoe, Yukon

599-013 OEM Direct Cross #’s 10367041, 15133519, 15192450, 15214766, 15832314, 15832316, 15855848, 21997426, 21997427

General Motors 2003-2004
Auto Dual Temperature Control
Avalanche, Escalade, Sierra, Silverado, Suburban, Tahoe, Yukon,

599-009 OEM Direct Cross #’s 10367042, 15105215, 15107730, 15137655, 15185639, 15195564, 15201969, 15222482, 15763065, 15832318, 15855849

Ford 2003-2010
Auto Temperature Control
Crown Victoria, Grand Marquis, Marauder

599-030 OEM Direct Cross # 3W7Z19980AA

Is your GM Truck with the 4.8L, 5.3L or 6.0L engine experiencing a rough idle? Or is your check engine light on, with codes PO300, PO171, PO174 and PO332?

These two conditions seem to be very common, and requires similar repair procedures (removal of the intake manifold). Gm has recognized these problems and has issued a parts revision and TSB (Technical Service Bulletin) to repair these symptoms.

First we will talk about a rough idle. Most vehicle owners complain about a rough idle or a misfire when the engine is cold, and as the engine warms up the problem goes away??? But, leaving your check engine light on, with codes PO300, PO171 and PO174. PO300 is a misfire code that is usually fixed by new ignition parts like spark plugs and wires. But, when accompanied by PO171 and PO174, this indicates a Fuel Trim problem. The engine may be running to lean, due to a intake vacuum leak. When your vehicles engine is cold, the PCM (power control module) is running in ‘closed loop’ a predetermined run program. As the engine reaches normal operating temperature the PCM switches to ‘open loop’ using the engine control sensors to read the data from the engine to refine the running condition. One of these sensors is a oxygen sensor, this monitors the air/fuel ratios in the exhaust to calculate the amount of fuel to deliver to the engine. With a vacuum leak the the computer controls can not calculate for the extra air in the engine, making a lean condition. The oxygen sensor sees the lean condition and the PCM increases the amount of fuel to the engine to compensate. This is called fuel trim, as the fuel trim enrichment reaches 25% or more adjustment the PCM sets a code for the problem.

GM has recognized two part problems with sealing of the plastic intake manifold, the intake gaskets and bolts. The original red/orange gasket has be revised to a teal green colored gasket were the material has been updated. The bolts are sleeved with a rubber crush washer and require a special torque sequence to insure a proper seal. The intake bolts should NEVER be reused!

GM has also issued a TSB (02-06-04-023A) for code PO332 (knock sensor), which may be heard as a mild to severe engine ping usually sounding worse on acceleration. This condition is a result of corrosion on the rear bank knock sensor due to water intrusion into the sensor cavity. This condition is more frequent on vehicles that the owner washes the engine compartment.

To correct the Knock sensor problem requires replacement of the rear knock sensor (their is also a front knock sensor,  we also recommend replacing) and building a dam (wall) around the sensor using RTV to divert water away from the sensor.

APDTY’s kit comes with Intake Gaskets, Foam Pads, Intake Bolts, RTV and Knock Sensor(s) and Optional  Wiring Harness

Tighten the intake manifold bolts in sequence, tighten on first pass to 44Lb in. On the final pass torque to 89Lb in.

What is a Electronic Throttle Body or commonly referred to as Throttle-By-Wire, Fly-By-Wire, Drive-By-Wire (DBW) or Throttle Actuator Control (TAC)?

Electronic Throttle Bodies? Where’s the throttle cable? As you may already know opening the hood in a modern car reveals systems alot different than that of years past. As engine life has been extended and engine controls have become more complex, longer-life and higher-reliability electronic components are required. These advances in electronic componets aid the Power Control Module (PCM) to stay within the programed perimeters for the best performance and emission regulations.  One of these components being the Electronic Throttle Control (ETC) system often referred to as throttle-by-wire, fly-by-wire, drive-by-wire (DBW) or throttle actuator control (TAC). Using a array of sensors the on-board computer system measures throttle demand, then sends out a signal (electronic command) to the electronic throttle body. This computer command is to operate a servo motor controlling the throttle plate/blade or butterfly.

What seems to be the failure of the Electronic Throttle Body is the plastic gear drive. A common problem of the throttle body bore has been a build up of gases from the EGR and PVC systems, combined with heat causes a formation of gummy residue. This gummy residue often restricts airflow causing poor or hunting idle and even stalling conditions. This residue can become so built up that it causes the throttle body plate/blade to stick, striping out the gear drive in the throttle body.

TechSmart™ has a complete line of New Electronic Throttle Bodies, offering a cost effective solution for repairing  failed electronic throttle bodies for many makes and models.

2010-2009 Ford Light Truck Expedition
2010-2009 Ford Light Truck F Series Fullsize Pickup
2010-2009 Lincoln Navigator

2007-2006 Cadillac CTS
2008-2006 Chevrolet Corvette
2009-2008 Pontiac G8
2006-2005 Pontiac GTO

2007-2006 Buick Rendezvous
2006-2005 Buick Terraza
2006-2005 Chevrolet Malibu / Malibu Maxx
2006-2005 Chevrolet Light Truck Equinox
2006-2005 Chevrolet Light Truck Uplander
2006-2005 Pontiac G6
2006-2005 Pontiac Montana
2006-2005 Saturn Relay

2008-2006 Buick LaCrosse
2006 Buick Rendezvous
2007-2006 Cadillac CTS
2006 Cadillac SRX
2007-2006 Cadillac STS

2006-2004 Cadillac SRX
2009-2006 Cadillac XLR
2006-2005 Pontiac Torrent

2004 Buick Rainier,
2006-2003 Cadillac Escalade,
2006-2003 Chevrolet Light Truck Fullsize Pickup
2007-2004 Chevrolet Light Truck G Series Fullsize Van / Express
2006-2003 Chevrolet Light Truck Suburban / Fullsize Blazer / Tahoe
2004-2003 Chevrolet Light Truck Trailblazer
2004-2003 GMC Light Truck Envoy,
2006-2003 GMC Light Truck Fullsize Pickup
2007-2004 GMC Light Truck G Series Fullsize Van / Savana
2006-2003 GMC Light Truck Suburban / Fullsize Jimmy / Yukon
2007-2005 Hummer H2

2004-2003 Oldsmobile Bravada
2007 Chevrolet Light Truck Colorado
2007 GMC Light Truck Canyon
2007 Hummer H3
2007-2003 Buick Rainier
2007-2003 Chevrolet Light Truck Trailblazer
2007-2003 GMC Light Truck Envoy
07-05 Pontiac Grand Prix
2007-2005 Saab 9-7
2007-2006 Chevrolet Impala

2007 Saturn Aura
2009 Saturn Vue
2009,2010 Buick Lucerne
2009,2010 Chevrolet Impala
2009-2006 Chevrolet Light Truck Uplander
2009-2006 Pontiac Montana
2009-2006,2010 Chevrolet Malibu / Malibu Maxx
2009-2006,2010 Pontiac G6
2009-2007 Chevrolet Light Truck Equinox
2009-2007 Pontiac Torrent

2001-1999 Cadillac Catera
2004-2003 Cadillac CTS

2002 Chevrolet Light Truck Trailblazer
2002 GMC Light Truck Envoy
2002 Oldsmobile Bravada

2008-2005 Pontiac Grand Prix
2008-2006 Buick Lucerne
2009-2005 Buick LaCrosse

2007 Chevrolet Light Truck Colorado
2007 GMC Light Truck Canyon
2007-2004 Saturn Ion
2007-2005 Chevrolet Cobalt

2006-2003 Chevrolet Light Truck Suburban / Fullsize Blazer / Tahoe
2006-2003 GMC Light Truck Suburban / Fullsize Jimmy / Yukon
2007-2003 Chevrolet Light Truck Fullsize Pickup
2007-2003 GMC Light Truck Fullsize Pickup

2009-2008,2010 Chevrolet Light Truck HHR
2009-2008,2010 Chevrolet Malibu / Malibu Maxx
2010 Chevrolet Light Truck Equinox
2010 GMC Light Truck Terrain

2008-2007 Chevrolet Malibu / Malibu Maxx
2009-2007 Pontiac G5
2009-2007,2010 Chevrolet Cobalt
2009-2007,2010 Chevrolet Light Truck HHR

2009-2007 Saturn Outlook
2009-2007 Saturn Vue
2009-2007 Suzuki XL-7
2009-2007,2010 GMC Light Truck Acadia
2009-2008 Chevrolet Light Truck Equinox
2009-2008 Pontiac Torrent
2009-2008,2010 Buick Enclave
2010 Buick LaCrosse

2009-2007,2010 Cadillac SRX
2009-2008,2010 Cadillac CTS
2009-2008,2010 Cadillac STS
2010 Buick LaCrosse
2010 Chevrolet Camaro
2010 Chevrolet Light Truck Equinox
2010 GMC Light Truck Terrain

2009 Chevrolet Light Truck Avalanche
2009 Chevrolet Light Truck Suburban / Fullsize Blazer / Tahoe
2009 GMC Light Truck G Series Fullsize Van / Savana
2009 GMC Light Truck Suburban / Fullsize Jimmy / Yukon
2009 Hummer H2
2009-2010 Cadillac Escalade
2009-2010 Chevrolet Corvette
2009-2010 Chevrolet Light Truck Colorado
2009-2010 Chevrolet Light Truck Fullsize Pickup
2009-2010 Chevrolet Light Truck G Series Fullsize Van / Express
2009-2010 GMC Light Truck Canyon
2009-2010 GMC Light Truck Fullsize Pickup

2009-2010 Ford Crown Victoria
2009-2010 Ford Light Truck E Series Fullsize Van
2009-2010 Ford Mustang
2009-2010 Lincoln Town Car
2009-2010 Mercury Grand Marquis

2009-2010 Ford Light Truck E Series Fullsize Van
2009-2008 Ford Mustang

2008-2006 Ford Light Truck Explorer / Sport / Sport Trac
2008-2006 Mercury Mountaineer

2005-2004 Ford Light Truck Explorer / Sport / Sport Trac
2005-2004 Mercury Mountaineer

2006-2003 Chevrolet Light Truck G Series Fullsize Van / Express
2006-2003 GMC Light Truck G Series Fullsize Van / Savana

2007-2005 Ford Five Hundred,
2007-2005 Ford Light Truck Freestyle
2007-2005 Mercury Montego

2009-2006 Ford Fusion
2009-2006 Mercury Milan

2010 Ford Light Truck Transit Connect

2006 Lincoln Zephyr
2009-2006 Ford Fusion
2009-2006 Mercury Milan

2002-2001 Chevrolet Light Truck Fullsize Pickup
2002-2001 Chevrolet Light Truck G Series Fullsize Van / Express
2002-2001 GMC Light Truck Fullsize Pickup
2002-2001 GMC Light Truck G Series Fullsize Van / Savana
1999-1998 Chevrolet Light Truck P Series Van
1999-1998 GMCLight Truck P Series Van

2004-2000 Chevrolet Corvette
2005-2004 Cadillac CTS

2002 Cadillac Escalade
2002 Chevrolet Light Truck Avalanche
2002-2000 Chevrolet Light Truck Fullsize Pickup
2002-2000 GMC Light Truck Fullsize Pickup

2008-2005 Pontiac Vibe

2004 Pontiac Grand Prix

2002-1999 Chevrolet Camaro
2002-1999 Pontiac Firebird

2009-2005,2010 Ford Mustang

EGR Problem? What does the EGR System do? How to fix, repair the most common failures of the EGR System. Replacing the EGR Solenoid and Transducer on Chrysler, Dodge, Plymouth, Eagle, Jeep, GMC and Mitsubishi vehicles.

What does the EGR system do?  The function of the EGR system is to reduce oxides of nitrogen (NOX) in exhaust emissions, reduces cylinder combustion temperatures and helps prevent spark knock. The EGR system allows a predetermind amount of exhaust gas to recirculate and dilute the incoming air/fuel mixture to reduce peak temperatures during combustion.

When is the EGR system needed? The amount of emissions NOx produced at low engine speeds is very small, and is not needed at idle. It is also not needed during wide-open throttle driving, to achieve efficient acceleration. Recirculation is required during cruising and non-wide-open acceleration at speeds between 30 to 70 mph, when NOx formation is highest.

The EGR system consist of a EGR Valve, EGR solenoid, EGR backpressure transducer, signal tube and hoses. The solenoid operation is controlled by Powertrain Control Module (PCM) and the EGR backpressure transducer operation is controlled by the exhaust system backpressure.

Most faluires of the EGR systems are due to the transducer and solenoid. TechSmart™  manufactured by SMP, now offers a quicker and more cost effective solution for replacing just the fualty transducer and solenoid, perfectly matching the OEM EGR valve specifications.

EGR System- Solenoid,Valve and Transducer

G28001 — 2000 Chrysler Voyager / Grand Voyager | 2000-1996 Chrysler Town & Country | 2000-1996 Dodge Light Truck Caravan / Grand Caravan | 2000-1996 Plymouth Voyager / Grand Voyager

G28002 — 1993-1990 Chrysler Imperial | 1993-1990 Chrysler New Yorker | 1993-1990 Dodge Dynasty | 1993-1991 Chrysler Dynasty | 1994 Chrysler Intrepid | 1995-1990 Chrysler Town & Country | 1995-1990 Dodge Light Truck Caravan / Grand Caravan | 1995-1990 Plymouth Voyager / Grand Voyager | 1995,1993 Chrysler Intrepid | 1995-1993 Chrysler Concorde | 1995-1993 Dodge Intrepid | 1995-1993 Eagle Vision | 1999-1996 Dodge Neon | 1999-1996 Plymouth Neon

G28003 — 1993 Jeep Grand Wagoneer | 1996-1992 Dodge Light Truck Dakota | 1996-1992 Dodge Light Truck Pickup – Fullsize / Ramcharger | 1996-1992 Dodge Light Truck Van – Fullsize | 1996-1993 Jeep Grand Cherokee

G28004 — 2000-1995 Chrysler Cirrus | 2000-1995 Dodge Stratus | 2000-1996 Chrysler Sebring

G28005 — 2002-2001 Chrysler Town & Country | 2002-2001 Chrysler Voyager / Grand Voyager | 2002-2001 Dodge Light Truck Caravan / Grand Caravan

G28006 — 1996-1995 Chrysler New Yorker | 1997-1995 Chrysler Concorde | 1997-1995 Chrysler Intrepid | 1997-1995 Chrysler LHS | 1997-1995 Dodge Intrepid | 1997-1995 Eagle Vision

G28007 — 2000 Chrysler Voyager / Grand Voyager | 2000-1996 Dodge Light Truck Caravan / Grand Caravan | 2000-1996 Plymouth Voyager / Grand Voyager

G28008 — 2000,1997 Chrysler Cirrus | 2000-1997 Dodge Stratus | 2000-1997 Plymouth Breeze | 1998-1997 Chrysler Sebring

G28009 — 1986 GMC Light Truck G Series Fullsize Van / Savana | 1996-1992 Dodge Light Truck Dakota | 1996-1992 Dodge Light Truck Pickup – Fullsize / Ramcharger | 1996-1992 Dodge Light Truck Van – Fullsize

G28010 — 2002-2001 Chrysler PT Cruiser

G28011 — 1997-1995 Chrysler Sebring | 1997-1995 Dodge Avenger

G28012 — 1989 Dodge Lancer | 1990 Dodge Light Truck Caravan / Grand Caravan | 1990 Plymouth Voyager / Grand Voyager | 1991-1989 Chrysler Daytona | 1991-1989 Chrysler LeBaron | 1991-1989 Dodge Daytona | 1991-1989 Dodge Shadow | 1991-1989 Dodge Spirit | 1991-1989 Plymouth Acclaim | 1991-1989 Plymouth Sundance

G28013 — 1998-1995 Eagle Talon | 1999-1995 Chrysler Sebring | 1999-1995 Dodge Avenger | 1999-1995 Mitsubishi Eclipse

G28014 — 1989-1988 Dodge Light Truck Pickup – Fullsize / Ramcharger | 1989-1988 Dodge Light Truck Van – Fullsize

G28015 — 2000-1998 Chrysler Sebring | 2000-1998 Dodge Avenger

G28016 — 1997-1996 Dodge Stratus | 1997-1996 Plymouth Breeze

G28017 — 2000-1999 Plymouth Voyager / Grand Voyager | 2002-2000 Chrysler Voyager / Grand Voyager | 2002-1999 Dodge Light Truck Caravan / Grand Caravan

G28018— 1992 Chrysler Dynasty | 1993-1992 Chrysler Daytona | 1993-1992 Chrysler LeBaron | 1993-1992 Dodge Daytona | 1993-1992 Dodge Dynasty | 1994-1992 Dodge Shadow | 1994-1992 Plymouth Sundance | 1995-1992 Dodge Spirit | 1995-1992 Dodge Light Truck Caravan / Grand Caravan | 1995-1992 Plymouth Acclaim | 1995-1992 Plymouth Voyager / Grand Voyager

G28019 — 1995 Dodge Neon | 1995 Plymouth Neon

G28020 — 2000 Chrysler Cirrus | 2000-1997 Dodge Stratus | 2000-1997 Plymouth Breeze

G28021 — 1996 Chrysler Sebring | 1996-1995 Chrysler Cirrus | 1996-1995 Dodge Stratus

G28022 — 1995,1993 Chrysler Intrepid | 1995-1993 Chrysler Concorde | 1995-1993 Dodge Intrepid | 1995-1993 Eagle Vision

G28023 — 1996 Chrysler Concorde | 1997-1996 Chrysler Intrepid | 1997-1996 Dodge Intrepid | 1997-1996 Eagle Vision

G28024 — 1994 Chrysler LHS | 1994 Chrysler New Yorker | 1994-1993 Chrysler Concorde | 1994-1993 Chrysler Intrepid | 1994-1993 Dodge Intrepid | 1994-1993 Eagle Vision

G28025 — 1996-1994 Dodge Light Truck Pickup – Fullsize / Ramcharger

How To Diagnose, Repair, Remove & Replace A Front Intermediate Shaft Bearing Assembly aka Front Axle Disconnect Assembly On A Chevy Trailblazer, GMC Envoy, Olds Bravada, Buick Rainier, Or Saab 9-7x

Well here is another part that is very common to fail with a bunch of different names to confuse you and us:

1. Front Differential Axle Disconnect Assembly (Most Normal People Call It This)

2. Intermediate Shaft Bearing Assembly (GM Dealers Call It This)

3. Splined Disconnect or Gear Pods

In lamans terms, this part basically disconnects or disengages the front drive axle when the driver switches from 4WD to RWD or 2-Wheel Drive. Their are 2 different versions of front differentials on these vehicles, One is called S4WD (Selectable 4-Wheel Drive) & A4WD (Automatic 4-Wheel Drive). The S4WD differential contains both an actuator & the axle disconnect. For our article, we will call it the FRONT AXLE DISCONNECT ASSEMBLY for the S4wd models and INTERMEDIATE SHAFT BEARING ASSEMBLY for the A4wd models, more info as you read.

Parts Involved: Image 1 is the Front Axle Disconnect (2 Versions GM Part #:15884292 or 15884291), Image 2 is the Front Differential Actuator (GM Part #: 12471631) which engages the front axles. Purchase both parts together here


front differential axle actuator

Here is information about the 2 different front drive axle(s), courtesy of General Motors:

S4WD- Selectable Four Wheel Drive Axle Description & Operation:

The image below shows the actuator (top) and how it bolts to the disconnect assembly(bottom)

Exploded view of axle actuator and the axle disconnect

The front drive axle on the S4wd or Selectable 4-Wheel Drive differentials use a disconnect mounted right next to the passenger side CV axle and oil pan. Their is both an actuator that is used to engage the front axles when 4WD is enabled & a disconnect assembly that is used to disengage the front axles when switched back to 2WD or Rear Wheel Drive.

Explode view of transfer case and axle disconnect with 4wd actuator

In the exploded view above,  the yellow box is the components of the 4WD axle disconnect assembly and the green box is the axle actuator. These parts are sold separately and if you are replacing the disconnect assembly, you should also strongly consider replacing the actuator as it must be removed to install the new disconnect assembly. The red box is the front differential.

When the driver switches to 4-Wheel Drive, the TCCM(Transfer Case Control Module or 4WD computer) sends a signal to the electric actuator mounted on the disconnect and it energizes a plunger to extend out and push the clutch fork and clutch fork sleeve out to engage the drive axles. This engages 2 gears inside the differential and makes the front differential act very similar to a non locking rear differential or in other words a semi-floating axle used on RWD cars for years. This is done because a traditional ring & pinion gear set is used to transmit the driving force from the engine and transfer case to the front differential. This type of front differential allows for the turning of the front wheels so each wheel can spin at different speeds during a turn and still use the power generated from the engine. This prevents your tires from being dragged across the pavement during a turn and more importantly prevents the internal gears from being damaged. The front drive axles are also CV axles and allow for turning also and absorbs much of the turning force.

A4WD- Automatic Four Wheel Drive Axle Description & Operation:

This part of the article we will call the front axle disconnect, the proper GM name of Intermediate Shaft Bearing Housing Assembly as this system, the name actually makes sense. This is because the differential intermediate shaft slides through the Intermediate Shaft Bearing Housing and rides on bearings inside the assembly. In fact bearing failure inside the housing is one of the biggest causes of replacement. Once the bearings start to fail, they will make noise and these noises are a symptom of the housing needing replacement. The A4wd front differentials are similar but they do not have an electric actuator and they do not actually use the disconnect assembly to disengage the 4WD. This is also one way for you to determine which system you have. If you look under the vehicle where the inner passenger side CV axle connects to the front differential, you will see the axle disconnect assembly. If a black plastic unit is attached to it, then you have the S4wd (selectable) and if you do not have it, then you have the A4wd(automatic). The image below shows the electronic actuator and the intermediate bearing assembly outlined in red.

actual image of a front axle disconnect with axle actuator for S4wd

The A4WD models uses the same differential carrier assembly, however the Intermediate Axle Bearing Housing Assembly is slightly different. The clutch fork, clutch fork sleeve, and gears have been replaced with a single splined sleeve that connects the right side drive axle to the inner axle shaft directly. This allows the passenger side CV axle to be directly connected to the intermediate axle shaft inside the differential. If the transfer case is activated by the PCM, then the clutch assembly within the transfer case controls the amount of torque applied to the front differential.

Ok, So now we know what these parts are and how they work. Next is the symptoms associated with a failed or failing Front Axle Disconnect/Intermediate Shaft Bearing Housing Assembly


1. Their is usually NOT a trouble code set set when these fail so a check engine or 4wd light may not even illuminate on the dash

2. The vehicle fails to engage into 2WD, 4WD, or AWD

3. Noise – A rattle in the front end is noticeable at lower speeds and no external components of the suspension or steering have play or damage

4.  Excessive play in the axle shaft connection inside the axle disconnect.

Remove & Replace Instructions:

1. Raise & support the vehicle properly, remove the passenger front wheel, splash shield, & then remove the passenger front CV axle.

2. On S4WD models, remove the electric axle actuator from the axle disconnect assembly by removing the 2 bolts and electrical connector. This part is also very common to fail, If this part has not yet been replaced, then we strongly recommend replacing it now or at a minimum test it. If you think about it, the axle actuator has gone through just as many cycles as the disconnect and if the disconnect failed, well then the axle actuator is probably right behind it.We have seen it over and over in our shop, not this exact part but parts similar to this, Think about the labor you are already doing and if it were my vehicle I would be replacing the actuator at the same time. If you have A4WD, then you can skip this step as you do not have this actuator on your vehicle.

3. Remove the wire harness clip located on the axle disconnect.

4. Remove the 4 bolts attaching the axle disconnect from the front differential. The images below show both systems:

A4WD system showing 4 bolts to remove assembly

S4WD showing removal of actuator and disconnect assembly

4. Remove the old disconnect assembly

5. Remove the new part from the box and remove the protective plastic plugs inside of each seal.

6. The new units are pre-greased internally from the factory, however just like most any seal, it is a good idea to apply a small amount of lube along the lip of each seal with your finger. This prevents the seals form being damaged when the metals shafts slide through them during installation.

7. Install the new unit and make sure it is flush to the oil pan.

8. Tighten the 4 axle disconnect attaching bolts to the differential to 35 foot lbs.
9. On S4wd electric shift models, clean the actuator on the point where actuator meets the internal shift fork of the new disconnect unit. Install the actuator, Tighten the 2 bolts of the electric actuator to the axle disconnect to 53 Inch Pounds

10. Reinstall the remainder of the items in the reverse order.

IMPORTANT NOTES:  Do not nick or cut the inboard oil pan inner shaft seal!!     Also the axle disconnect must fit flush against the oil pan in order for the inner axle shaft to line properly!!

Coil Spring Conversion Kit Installation Instructions, Chevrolet Trailblazer 2002 – 2009

Rear Air Bag Suspension To Coil Spring Suspension Conversion Kit Installation Instructions For The Following Vehicles:

Chevrolet Trailblazer 2002 – 2009

GMC Envoy 2002 – 2009

Chevrolet Trailblazer EXT 2002 – 2006

GMC Envoy ESV 2002 – 2006

chevy trailblazer coil spring suspension conversion

CAUTION: Working with coil springs can be dangerous, Follow all instructions carefully. Use EXTREME caution when working around compressed coil springs. If you do not feel comfortable handling this job, we recommend you bring it to a trusted repair shop.

Removal of air springs:

1)      Support vehicle in air, the rear suspension MUST be fully extended,  in other words hanging freely with no supports under it, to do this, be sure the vehicle is supported by the FRAME and not the rear differential or control arms.

2)      Remove both rear wheels

3)      Locate the air suspension compressor located behind the passenger rear wheel.

4)      Unbolt the compressor bracket and lift upwards to unhook it from the frame.

5)      Release the air pressure from the air springs by disconnecting the air lines going to the compressor.

6)      Disconnect the electrical connectors from the compressor and set aside. The compressor assembly will not be reinstalled.

7)      Release the top of the rear air-springs, there is a locking tab that must be depressed while you turn the top of the air-spring to unclip it from the mounting bracket. Some models have a small hole in top of the mounting bracket to access the locking tab.

8 )      Once air-spring is released, remove the air line by pressing down on the steel fitting going into the air-spring and pulling out on the air line at the same time and remove the air-springs from the vehicle.

9)      Remove both lower shock bolts. This will allow the axle to hang freely on the control arms.

Installation of coil springs:

1)      With the rear differential hanging freely, place the new coil springs on the spring perches.

2)      With a floor jack, CAREFULLY jack up the rear axle below the differential housing (pumpkin) until the holes for the shocks align with the hole in the rear differential shock bracket.

3)      Install the bolts for the shock absorbers and tighten the shock nuts to 70 ft/lb.

4)      Reinstall the wheel assemblies, lower vehicle, and torque the lug-nuts to 100 ft/lb

Disabling the Air-Suspension System:

                As long as the air suspension compressor remains disconnected, you will not have any warning lights or malfunctions due to the coil spring conversion.

GMC/Chevy 2500 & 3500 Pickups (Includes HD Models) Front Wheel Hub Bearing Replacement Instructions

Here is another set of instructions we found online. We copied and pasted them here for you and we added a few little tidbits. Thanks for visiting our site and we hope these will help you. You can also call our ASE certified staff with any questions at 1-866-770-2771. We provide these instructions free of charge and these are meant as a guide only.

How To: Replace Front Wheel Hub Bearing Assembly on 2500HD/3500SRW (dually similar):

Preface: The front wheel hub bearing assemblies on the Chevy and GMC 2500 and 3500 series trucks are very expensive to replace. The good news is that you can follow these instructions and do this job yourself and save several hundred dollars. This job can cost $500-$1000 at a repair shop and if you have done a brake job before, then you should be capable of handling this job.


You can tell if the wheel bearing is failed or failing by a couple of different methods. The most common early symptom is noise. The noise will usually start as a slight growling or roaring sound. This noise typically can be heard from 30-50 MPH and the frequency will match the speed of the vehicle. Sometimes the noise will come and go and the longer you wait to deal with it, usually the louder it will get until it finally fails completely. You really should get into this job well before the bearing fails completely because further damage and expense can occur. Basically if you start hearing a noise, then check it out fast. Some diesel trucks are loud and make it difficult to hear the noise from the bearing so this next inspection is good to do at-least once a year or have a shop do it every oil change.  by jacking the truck up til the wheel is off the ground, grabbing the top and bottom of the tire and try to wobble it in and out. Their should be zero movement. If the wheel wobbles and it pivots from the center of the wheel, then the bearing is the most likely culprit. If their is play and the pivot point is toward the front or back of the wheel or from the top or bottom, then a through front end check should be performed. ANY movement is wear and tear and requires a thorough inspection. Ours were worn to the point of more than 2″ slop at the tire with 50,000mi on the truck. With that said, we must admit that we do have oversize tires and rims and we do a little mudding now and then.

Auto Zone $364.69
Advance Auto Parts $294.99
Napa Auto Parts $319.99
GM Dealer $390.00
The best price by far is These guys wholesale auto parts and sell directly to the public. You can save big bucks by purchasing from them and using these instructions. Also is their instructional website that has many useful instructional videos for all kinds of parts. They are ASE certified technicians and have extensive knowledge that you usually cannot find at a regular parts store.

The Hub Bearing Assembly comes with an ABS wheel speed sensor with cable and also has the studs pre-installed. GM has recently updated the part number to #15225770 or AC Delco #FW289. Retail for the unit can be as high as $450 ea, to a low of $190 ea, so it pays to shop around.

Let’s Begin/

What you will need:

You will need:

Floor jack

Jack stand

15mm socket and ratchet, wrench will work if you are strong.

21mm socket and BIG ASS breaker bar. Cutting torch will have better luck than a wrench on this *****.

36mm socket and breaker bar. Nut is actually 35.5mm, so a 1 3/8″ socket can be beaten on it.

Sharp flat blade screwdriver.



Large C-Clamp.


In picture, not absolutely necessary – impact wrench.

Not in picture, something a foot tall and will support 20lb, like a toolbox.

And last but certainly not least: about 3 beers per side, although after 5-6, some bloody knuckles are very possible

Step 1:

Jack side of truck up, and put a jack-stand under it. Use frame rail.

Remove Wheel.

Step 2:

Unplug the wheel sensor wire near the top of the shock. Look closely at the sensor connector and you can see how it simply unclips and slides apart. The new Hub will come with a new connector on the bearing side of the wire, just in case the plastic tabs break.

Step 3:

Use C-Clamp to compress the brake pistons so it will be easy to reinstall. If you are replacing the brake pads and rotors at this time (perfect time to do it), then fully compressing the pistons into the caliper is necessary. Technically the proper way to do this is to drain the brake fluid. If you have never flushed or bled the brakes, then this is a great time to learn. The safest way to do this is attach a hose to the bleeder screw and put the other end into a suitable container. Then, open the bleeder screw, slowly compress the brake caliper, and brake fluid will fill the container. We do not recommend pumping the brake pedal to bleed the brakes unless you are well versed in hydraulic and ABS brake systems. If you simply take the cap off of the brake master cylinder (under the hood), then you allow the brake fluid to gravity bleed out into the container. You can add fresh clean brake fluid to the master cylinder and watch the fluid coming out until it is also clean. Then snug down the bleeder screw and disconnect the hose. You can do this to the remaining wheels and then you have flushed your entire brake system, This is something that should be done every 2-3 years.

Step 4:

There are 2 21mm bolts that hold the brake caliper frame to the axle support. THESE ARE TIGHT!!! Rotate the steering to get to them easier. Remove the bottom, then loosen the top one so you can remove it with your fingers. You will need to have something ready to support it when you remove the brake assy. Do not allow the caliper to hang from the brake hose or you will most likely have to replace the hose.

Step 5:

Pull the top bolt and set the brake assy on something that will not stress the brake line. You can destroy a brake line by hanging that much weight on it.

Step 6:

In this picture, the lug at 11 o’clock and 5 o’clock have a retaining washer that holds the disc on the hub for assembly purposes. Remove these by rotating them with a screwdriver, then pry them off. You do not need to re-install these, I suggest you throw them away. Once they are removed, you can pull the disc off the hub. If it does NOT come off easy? You may need a flat heavy hammer to tap it off. Any damage to the rotor or if you noticed any blue coloring (overheated) in the rotor, pad & rotor replacement is recommended.

Step 7:

Pry the center dust cover off with a sharp flat blade screwdriver. Be fairly gentle as you will reuse this. This keeps the nut and threads inside cleaner and less rusty then exposed areas.

Step 8:

That nut in the center keeps the axle from wandering too deep into the differential. Other than that, it does nothing. It is not a load component. It measures 35.5mm, you can remove it with a 36mm socket and breaker bar or tap a 1 3/8″ socket onto it. If the truck is in 4WD with the truck in park, it will not spin the hub. The nut is a locking nut, so it will be tight most the way off. A Pneumatic impact gun can be used to quickly remove the nut, however do not re-install the nut with the impact gun.

Step 9:

Once the nut is off, spray some WD40 into the center spline, then tap the axle into the hub gently until it stops. It will move about 1″. This will make it easy to pull the hub off when it’s time.

Step 10:

There are four 15mm bolts that hold the hub on. These are also pretty tight. If you turn the steering wheel, it makes them easier to remove.

Step 11:

The hub should slip right out. You might have to tap the axle a bit more while holding the hub out from the base. Clean all mating surfaces, grease the o-ring in base. Dust shield faces forward.



Hub and Bearing Assembly to Steering Knuckle Bolts – 180 N·m / 133 lb ft

Axle Shaft Nut – 210 N·m / 155 lb ft

Caliper Mounting Bracket to Knuckle, Front – 300 N·m / 221 lb ft

Here’s the new hub/bearing assy. There is some electrical tape on the wire holding them together, tear it off.

Line up the spline to the holes with the wire at TDC. If the bolt holes do not line up, you can either take the truck out of 4WD, or pull it off the spline and try to align it better. I suggest align it better. There is a lot of slop in the axle rotation, so you don’t have to precisely get the right tooth on the spline for it line up. Screw the axle nut on by hand to hold it in place.

Use a few drops of Blue Loctite (yes I know it comes in a red bottle) on the 15mm bolts, and bolt the hub back down. Don’t forget the dust shield. The wire goes UNDER the tab on the dust shield.

Tighten down the axle nut and washer on the axle. Tap the dust cover back on with the handle of the hammer.

Replace the rotor.

Hold the brake pads apart with your fingers and slide the brake assy onto the rotor. Use loctite and reinstall the two 21mm bolts. Do I know the torques? Uh… REAL tight? (see torque specs above)

Snap the 4 wire holders into the same holes the old one came out of, and reconnect the connector near the shock.

Put wheel back on, lower truck..

IMPORTANT, pump the brakes to re-position the calipers!!!

Start engine and pump the brakes slowly several times. When you pushed the pistons back into the calipers, they are still sitting far away from the rotors and YOU WILL HAVE NO BRAKES.

Road test, and finish the last beer.

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