Service 4wd

dudg · December 26, 2007

When running my 2005 Suburban K2500 in Auto 4WD the warning "SERVICE 4WD" will come up in the DIC. I am unable to switch back to 2WD unless I turn off the ignition and start it again. Any ideas?

Thanks

jemurray · December 27, 2007

It could be the sensor in the transfer case or the motor itself (in the transfer case). Since it is showing "Service 4WD", it is probably the sensor. It wasn't too hard to replace, but I had to drop the front shaft on my 2005 GMC Sierra 1500 Quad Cab.

GMTRUCKTECH · December 27, 2007

you can thank me later

Subject:Service 4WD Light Illuminated, DTC C0374 Set (Inspect Wiring Harness to Transfer Case Speed Sensors, Replace Wiring Harness) #05-04-21-003B - (08/20/2007)

Models:2004-2007 Buick Rainier

2003-2007 Chevrolet Avalanche, Silverado Classic, Suburban, Tahoe, TrailBlazer, TrailBlazer EXT

2003-2007 GMC Envoy, Envoy XL, Sierra Classic, Yukon, Yukon XL

2003-2004 Oldsmobile Bravada

2005-2007 Saab 9-7X

with Four Wheel Drive or All-Wheel Drive

and Active All-Wheel Drive (RPO NP4) or Active Two-Speed (RPO NP8) Transfer Case

This bulletin is being revised to add the 2007 model year, remove the Escalade model and update information in the Correction section and Parts Information. Please discard Corporate Bulletin Number 05-04-21-003A (Section 04 -- Driveline/Axle).

Condition

Some customers may comment on intermittent illumination of the Service 4WD light. Upon investigation, the technician may find DTC C0374 set. The customer may also comment on intermittent erratic operation of the 4WD or AWD system after driving through rain/snow or simply going through a car wash.

Cause

The speed sensor signal may have become corrupted. Possible openings in the speed sensor wire insulation (twisted pairs) can allow water intrusion. Also, wire connections contaminated by water may result in short circuits and erroneous speed sensor readings. This most often occurs on the rear speed sensor circuit.

Correction

Inspect the wiring harness to the transfer case speed sensors. On Rainier, TrailBlazer, Envoy and 9-7X models, fabricate a replacement speed sensor harness between the C101 connector and the speed sensors. Completely inspect and test all wiring . Refer to Speed Signal, Front Axle Actuator, and Indicators schematic in SI.

Replace the affected twisted pairs. Do not over-twist the two wires in the replacement harness. Wires should be twisted at a rate of 9 revolutions per foot . Use service connector pack, P/N 88987993, at the speed sensor end and terminal, P/N 15326267, at C101.

Terminal testing tools and service terminals can be found in Terminal Repair Kit J 38125. Terminals are available from SPX/Kent-Moore. Call 1-800-GM-TOOLS (1-800-468-6657).

The smaller transfer case harness splices into the larger chassis harness a few inches in front of the crossmember. The chassis harness routes along the left side of the frame under the driver door area. Use nylon tie straps to secure the fabricated harness to the main chassis harness between the transfer case and C101.

On the full-size pickup and full-size utility models, replace the 2.2 m (88 in) pigtail harness that runs from the C151 connector under the hood to the transfer case. Use either harness, P/N 15224661 or 15224663, depending on vehicle equipment. Refer to Propshaft Speed Sensors, Front Axle Actuator and Transfer Case Shift Control Switch schematic in SI.

Important: Technicians should verify the integrity of the splice joints after the repair. All splice joints and connections should seal properly against water or a repeat condition can occur.

Parts Information

Part Number

Description

15832722

Harness Asm-Transfer Case Sel

(4WD Full-Size Pickup/Utility w/NP8 and without Four Wheel Steering (NYS)

15224663

Harness Asm-Transfer Case Sel

(4WD Full-Size Pickup/Utility w/NP8 and Four Wheel Steering (NYS)

88987993

Connector-w/leads, 2-way, Female (Speed Sensor)

(All Vehicles)

Warranty Information (excluding Saab U.S. Models)

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

N6630

Wiring And/Or Connector-Transmission/Transfer Case/Transaxle/Front and Rear Axle Control - Repair or Replace

Use published labor operation time

Warranty Information (Saab U.S. Models)

For vehicles repaired under warranty, use:

Labor Operation

Description

Failed Object

Fault/Reason

Location Code

Warranty Type

Repair/Action Code

Labor Time

3714901

Wiring And/Or Connector-Transmission/Transfer Case/Transaxle/Front and Rear Axle Control - Repair or Replace

37149

67

0

01

Use Published Labor Operation Time

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

Document ID# 2004248

2005 Chevrolet Chevy Suburban

dudg · December 27, 2007

Thanks for the great info!

gmtech4 · December 28, 2007

Thanks for the great info!

Rodger ,you are giving out missinformation,do not asume he has this code,and fire this bulletin,this guy needs to take it to a dealer,simple,scan it ,simple,fix it,I have done a thousand encoder sensors & reprogram for a 327 code ,it is possible he has that to ,stop being a hero,give possibilites not for sures,get it.

Nice rig · December 28, 2007

I don't mean to be a jackass, but is there a chance that the 4wd need serviced??? TC fluid level good? Just putting it out there.

gmtech4 · December 28, 2007

I don't mean to be a jackass, but is there a chance that the 4wd need serviced??? TC fluid level good? Just putting it out there.

your not a jackass ,the message does not mean to get the oil chg'd,it means there is a code in the TCCM and instead of an SES light ,they put in a message

skills4lou · December 28, 2007

Thanks for the great info!

Rodger ,you are giving out missinformation,do not asume he has this code,and fire this bulletin,this guy needs to take it to a dealer,simple,scan it ,simple,fix it,I have done a thousand encoder sensors & reprogram for a 327 code ,it is possible he has that to ,stop being a hero,give possibilites not for sures,get it.

Hey big guy, calm down. All he did was post some great info on a COMMON problem and how GM stealerships are supposed to check it out. Maybe the OP is like me and prefers to fix it himself. So GMtrucktech was posting an official GM bulletin related to the question dudg asked. How is that "missinformation"? Perhaps you might stop being such an anti-hero, and realize that most people on here post information that they feel may be useful. Most people realize that the info on this (or any website) is just FYI, and each individual case may be different. Get it?

Dudg, another possibility is the actual switch in the dash has gone bad. Do a search for "bad 4WD switch" and see what pops up.

gmtech4 · December 28, 2007

Thanks for the great info!

Rodger ,you are giving out missinformation,do not asume he has this code,and fire this bulletin,this guy needs to take it to a dealer,simple,scan it ,simple,fix it,I have done a thousand encoder sensors & reprogram for a 327 code ,it is possible he has that to ,stop being a hero,give possibilites not for sures,get it.

Hey big guy, calm down. All he did was post some great info on a COMMON problem and how GM stealerships are supposed to check it out. Maybe the OP is like me and prefers to fix it himself. So GMtrucktech was posting an official GM bulletin related to the question dudg asked. How is that "missinformation"? Perhaps you might stop being such an anti-hero, and realize that most people on here post information that they feel may be useful. Most people realize that the info on this (or any website) is just FYI, and each individual case may be different. Get it?

Dudg, another possibility is the actual switch in the dash has gone bad. Do a search for "bad 4WD switch" and see what pops up.

thx for your input,I am a gm tech,he still needs to have it scanned ,rodgers bulletin was for a code ,there is several bulletins for TCCM codes ,do you get it?

GMTRUCKTECH · December 28, 2007

Thanks for the great info!

Rodger ,you are giving out missinformation,do not asume he has this code,and fire this bulletin,this guy needs to take it to a dealer,simple,scan it ,simple,fix it,I have done a thousand encoder sensors & reprogram for a 327 code ,it is possible he has that to ,stop being a hero,give possibilites not for sures,get it.

Hey big guy, calm down. All he did was post some great info on a COMMON problem and how GM stealerships are supposed to check it out. Maybe the OP is like me and prefers to fix it himself. So GMtrucktech was posting an official GM bulletin related to the question dudg asked. How is that "missinformation"? Perhaps you might stop being such an anti-hero, and realize that most people on here post information that they feel may be useful. Most people realize that the info on this (or any website) is just FYI, and each individual case may be different. Get it?

Dudg, another possibility is the actual switch in the dash has gone bad. Do a search for "bad 4WD switch" and see what pops up.

thx for your input,I am a gm tech,he still needs to have it scanned ,rodgers bulletin was for a code ,there is several bulletins for TCCM codes ,do you get it?

JUST TRYING TO HELP A FELLOW TRUCK GUY. Not a newbie gmtech4 been working on gm trucks since the tender age of 12 and been at the dealer for 10 years holding down the truck department so relax and drink a beer bro. Your right it could anything but trying to give as much info as possible. Later

gmtech4 · December 29, 2007

Thanks for the great info!

Rodger ,you are giving out missinformation,do not asume he has this code,and fire this bulletin,this guy needs to take it to a dealer,simple,scan it ,simple,fix it,I have done a thousand encoder sensors & reprogram for a 327 code ,it is possible he has that to ,stop being a hero,give possibilites not for sures,get it.

Hey big guy, calm down. All he did was post some great info on a COMMON problem and how GM stealerships are supposed to check it out. Maybe the OP is like me and prefers to fix it himself. So GMtrucktech was posting an official GM bulletin related to the question dudg asked. How is that "missinformation"? Perhaps you might stop being such an anti-hero, and realize that most people on here post information that they feel may be useful. Most people realize that the info on this (or any website) is just FYI, and each individual case may be different. Get it?

Dudg, another possibility is the actual switch in the dash has gone bad. Do a search for "bad 4WD switch" and see what pops up.

thx for your input,I am a gm tech,he still needs to have it scanned ,rodgers bulletin was for a code ,there is several bulletins for TCCM codes ,do you get it?

JUST TRYING TO HELP A FELLOW TRUCK GUY. Not a newbie gmtech4 been working on gm trucks since the tender age of 12 and been at the dealer for 10 years holding down the truck department so relax and drink a beer bro. Your right it could anything but trying to give as much info as possible. Later

we both care ,that is obvious ,take care rodger,enjoy the warm winter,you )(*&^%%$$,lol,cya-Rob-

dudg · January 31, 2008

Turns out the tech found a code C0374. Tested a bad Encoder motor. And replaced the Actuator.

Thanks for all your help

minibike132 · January 31, 2008

you can thank me later

I think i'd be thankful I didn't throw a speed sensor and spend a couple of hours twisting a pair and repining connectors without a code to go by.

Hey big guy, calm down. All he did was post some great info on a COMMON problem and how GM stealerships are supposed to check it out. Maybe the OP is like me and prefers to fix it himself. So GMtrucktech was posting an official GM bulletin related to the question dudg asked. How is that "missinformation"?

It's misinformation if all you have to go by is a vague description of a problem and you give a bulliten as a fix saying you can thank me later, as if this could be the only fix, I've had at least a couple hundred service 4WD messages and never used that bulliten as a fix.

Most people realize that the info on this (or any website) is just FYI, and each individual case may be different. Get it?

I'm not trying to beat up anybody or side with anyone but this is a new fix to an old post. We could have saved some time and probably some money if we found out a code without shooting off a bulliten. There are probably a hundred Service 4WD bullitens.

Alot do, not most. When you go to the Ask the GM tech link my guess is most think your getting qualified answers not a guess.