Do you have a 4X4 S-10, Sonoma, Blazer Or Jimmy?? Did your TCCM go out on you?
The circuit boards in the original TCCM were poorly made, and after a few years of heat and cold, they fail to function any more. There are no repairable parts in a TCCM module; the whole module must be replaced.
Replacing your TCCM with a new Updated GM version will:
-turn off the “service 4WD” light”
-Bring back the orange lights on the selector switch
-Restore the functionality of the 4WD
Note : The original part numbers on the modules have all been updated, if you are not getting the part number you are getting the old version, and will have the same problems again.
The old numbers on the modules were: 15748800, 15040103, 12577412 OR 15154323
The TCCM modules go bad quite often, but there are 2 things you need to check first, before spending a lot of money for a new GM module.
If your ATC Fuse is blowing with the old module or the new module please read the following information.
We have seen many harness problems at the pinch weld above the transmission where the harness runs down to the encoder. It is very hard to see in the truck, so you have to disconnect the harness and pull it up from the top to see if it is chaffed and shorting to ground in this area. We have had to rerun the wires from the TCCM to the encoder motor A/B circuits, and from the under hood fuse box, using 14 gauge wire, to correct issues of blowing this fuse and use a 25 amp fuse , instead of the 20 amp. There has to be a short to ground, or binding in the transfer case, to blow the ATC fuse. The the problem is in the transfer case, since it has problems getting it in and out of 4 low), and/or the harness shorted. If you buy a new TCCM and If you still have this issue, the TCCM is not defective.
The next thing to check is the most simple:
Pull the #8 Fuse under the Hood, and let the truck sit for 30 minutes. Re install the fuse, and try out your 4X4 This resets the module sometimes, and will make it work again. This does not always work, and sometimes only works temporarily.
Don’t buy it from the dealer. The dealer requires you to program the TCCM, you can buy a pre-programmed TCCM here.