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Fixing/finding error codes on the Electronic 4 Wheel Drive


red94fourdoor
10-19-2005, 04:10 PM
I copied the following from s-10 forum. I see a lot of member having problems with their electronic transfer cases not allowing their 4 wheel drive to work.


All this info helps as well that I wrote on another forum:

Well, through everything I have gone through with this electronic 4x4, I figured I would share my knowledge as best as I can. If anyone thinks something should be added, feel free to. This is also from gathered information on other posts.

***HOW TO CHECK WHAT IS WRONG***

You will probably know when your 4x4 has failed when you needed it in the mud pit. Mine, for instance, failed by not doing anything when I hit the 4HI button. However, it would go into 4LO.

To read the codes for the 4x4 with electric shift transfer case, install a jumper wire from terminals "J" and "A" on the ALDL (12 pin connector under the driver's side dash)

The lights on the 4x4 indicator (switch) will flash in a pattern, there are only 4 codes, one flash is code one, 2 flashes is a code 2, and so on...

Code "1" is "RAM standby power" and is considered normal, may be caused by clearing the codes.
Code "2" is "Encoder fault"
Code "3" is "TCCM motor circuit"
Code "4" is "RAM/ROM failure"

If you have the codes 2 or 3 check all the encoder motor connections at the transfer case, if OK it will need a new encoder motor assembly.
If you have code 4, replace the TCCM.

Make sure all connections are good and no corrosion, and then it's either an encoder or TCCM.

***TO FIX THE TCCM***

The TCCM is located behind the glove box, and is accessed from underneath the dash. To remove, the kick panel and black cover come off. Then a 1/4" screw holds the "brains" in the dash. The middle computer is the Truck's brain, the one on the backside is the TCCM, and on the front is the small ABS computer. Simply loosen the 2 10mm nuts on each side, and they will separate.


***WAYS TO FIX THE ENCODER MOTOR PROBLEM.***

This is the most common problem, and was my problem.

Cheap way - To clear the codes and reset the computer, pull the 5 amp TCCM fuse, located at the bottom of the fuse box. Wait at least a half hour, and then replace the fuse. Turn the ignition key to run, wait for the 4x4 lights to blink, and then turn off. Repeat 5 times, and then start the truck.

Decent price way - I just went and bought a rebuilt encoder motor from a company off of Ebay. Their company is www.northernautoparts.com The part cost me around $140 with a 1 year warranty and $38 core refund when I send the old one back.

Expensive way - buy a brand new one from GM for over $300.

***HOW TO INSTALL THE NEW ENCODER MOTOR***

Lucky way - Only thing that needs to be removed is the encoder motor itself. Tools needed are a 10mm hand wrench and a 8mm and 10mm socket wrench. The 10mm socket will work on the upper and lower bolts, while the regular wrench is needed for the middle bolt. (Tight squeeze). The 8mm socket is for the electric plug.
Then, just pull out, and wiggle it out of the truck. Install in reverse order.

Unlucky way - This means the encoder motor did not just wiggle out. Now the front drive shaft will have to be removed at the transfer case. Then, a yolk puller is needed in order to remove the yolk from the transfer case. Once this is done, go to the directions in lucky way.

This is as much knowledge as I have at the moment about the beautiful setup called the electronic pushbutton 4x4. Thank you to all that have helped me, and hopefully this will help others in fixing the future.

-=Glenn=-

I wish to Thank Glenn aka gmshades from s-10forum.com


I followed everything and I finally figured out what was wrong.
Thanks Glenn


Can we make this a sticky?

denise2580
10-19-2005, 08:16 PM
Thanks for the information! Any and all info is appreciated! I have read other posts and am really confussed by the fact that most of the problems are that people don't have 4wd and my problem is the opposite and it goes in by itself even if the buttons don't say so! I can tell as soon as it starts to chirp and jump when I turn and park. From what I have heard this is only a problem when you don't use the 4wd then it goes bad and I tend to baby my cars, they don't go out in bad weather! Yes I know I am nuts! I have purchased all 5 service manuals from gm and they have not been a whole lot of help yet, I guess I am just out of touch with this stuff I stopped working on cars when they got smarter that I am so this whole computer thing totally messes with me! Thanks and have a great night!

red94fourdoor
10-20-2005, 09:11 AM
Can I get this made into a stickie???

red94fourdoor
10-21-2005, 03:10 PM
Can I get this made into a stickie???


CAN I GET A MOD TO MAKE THIS A STICKY

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