Service 4wd - Chevrolet Forum - Chevy Enthusiasts Forums

Go Back   > >
Log In 

Colorado The compact pickup from Chevy, including the new Duramax Turbo-Diesel Colorado.

Chevrolet Colorado
Platform: GMT 350, GMT 31XX

LinkBack Thread Tools Search this Thread
Old 10-01-2008, 03:55 PM
Thread Starter
Join Date: Oct 2008
Posts: 1
Default Service 4wd


My Serv 4wd light is on and I am trying to figure out how to diagnose it.

05 Chevy Colorado LS
3.5 l
Z71 Crew Cab
about 38,000 miles

I took it to an auto zone, but they were unable to read the codes for the 4wd. I disconnected the battery to try and reset the codes, but it came back on almost immediately. I can't switch to 4wd, in fact there isn't even an amber light on saying it is in 2wd. I am stuck feeling like the only possibility is to take it to a dealership. Any ideas on how I can pull the codes on the 4wd system? Thanks!
Reply With Quote
Old 10-02-2008, 04:59 AM
Join Date: May 2008
Posts: 88
Default RE: Service 4wd

There will usually be a code e.g. DTC C0327 encoder motor circuit fault. But you need tech2 to pull the codes.

The transfer case shift control module has 4encoder circuits, and each circuit is supplied 12volts. These 4circuits are A, B, C, and P, and each circuit runs to a switch located inside the encoder/motor assembly. When a particular encoder circuit is active, the switch is closed, and the 12volts are grounded by the switch inside the encoder.
The transfer case shift control module supplies 12volts on all the circuits. The module can interpret the location of the transfer case shift position when the circuits are grounded.
This DTC detects a fault when it compares the shift sequence/strategy to a chart located in read only memory (ROM), within the electronic control unit (ECU), within the transfer case shift control module. This is accomplished by the module reading the different combinations of encoder signals being grounded while others remain high depending on what mode or range the transfer case is in.

The transfer case shift control module sets the DTC when the encoder signals do not match the chart contained in ROM. This DTC can be set while no shift is requested or while a shift is being performed.
Reply With Quote
Old 10-02-2008, 10:46 PM
shawnvw's Avatar
Super Moderator
Professional Mechanic
Join Date: Jan 2008
Posts: 2,571
Default RE: Service 4wd

other mom and pop shops should be able to read the codes for you. AutoZone will probably just have a cheapo code reader, where as another shop will have some money invested into a good scan tool. If you don't want to go to a dealership, i'd try a local shop
Reply With Quote
Old 10-13-2010, 10:00 PM
CF Beginner
Join Date: Feb 2010
Location: bronx
Posts: 2

where is the transfer case module located
Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
2015 Silverado 1500 - Service 4WD and Service StabiliTrak abj182 Silverado & Fullsize Pick-ups 2 08-05-2015 08:58 AM
Service Ride Control and Service 4wd Catfan1963 Tahoe & Suburban 1 10-30-2014 08:38 AM
2005 Chevy Sub 4wd 1500 issue... "Service 4wd" D Chevy Tahoe & Suburban DIY and Useful Threads 0 09-17-2012 12:06 PM
1998 Tahoe LT 4WD wire harness to tranny/4wd waller2003 Tahoe & Suburban 0 10-19-2009 09:49 PM
Help, Went into 4WD because of snow and now it is STUCK in 4WD!!! DianaT General Tech 4 11-29-2007 12:12 AM

4wd, case, chevrolet, chevy, code, encoder, module, motor, reader, reads, reset, serv, service, silverado, transfer, z71

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -5. The time now is 10:18 PM.