some of you might of experienced or are about to experience 4x4 issues with the electronic shift transfer cases. things like it suddenly going into 4 hi or starting the truck and it's in 4 lo are becoming common place at the shop here. on effective fix is to clean and tighten the chassis ground right behind the driver's front wheel. there are 2 grounds here bolted to the backside of the body mount. this applies to all 99-current fullsize 4x4 trucks and utilities.


1- remove the bolts for the grounds and THROW them away. DO NOT reuse these as they will not tighten up in the body mount like they should.

2- clean both sides of the body mount down to bare metal.

3- clean both sides of the grounds with a wire wheel or sandpaper.

4- drill out the threads in the body mount.

5- install new bolts with flat and lock washers or a locking nut.

6- treat the area with a rust fighting paint, battery terminal seal, etc.

 

Thanks for the TIP, i'll remember that one.

Steve

 

what trucks does this refer to ? GM , Dodge, Ford?

 

GM.

 

any particular model transfer cases?

 

I havent had the issue yet , however I have had a mystry service 4x4 light that came on the DIC several times . I just hit the odometer setting and it goes away ! Would this be a start ?

 

i think it would be. that's fixed quite a few of them and it's something u can easily do urself.... for free. if it comes back after then get it scanned and lemme know wut code ya git.

 

Got any pics of where the ground hits the frame?

I havne't had any problems with my 02 but who knows??

 

well yes and no. i have the gm location drawing. it's ok but not as nice as a picture.

 

being in texas i really doubt you'll have this issue. it's more in the northern climates that use road salt and stuff.

just to add some stuff here. here's some typical failures we've seen at our dealership for the 4x4.

code-- c0327-- clean the frame grounds and check battery grounds as i stated above. if that does not fix it, 95% of the time our flow charts lead to replacing the 4x4 shift motor on the t-case. in some rare instances we've seen the transfer case control modules fail but it's not very common.
the TCCM needs to be reprogrammed by the dealer once replaced.

code-- b2725-- replace the 4x4 shift button assembly on the dash. 99% of the time we get this code, this part is the failure.

hope some of this helps.