2005 Gmc 4x4 Switch Problem

jemurray · November 30, 2007

I have a 2005 GMC Sierra Crew Cab with only 42000 miles on it (babied) that has decided to start switching itself into four wheel drive (high) by itself. It has done it three times now. I have the button on the dash (2W/4WH/4WL). I have to pull off on the side of the road, shut off my vehicle, then crank it. I can then hit the 2W button and it will switch back in.

Anybody have an idea about this? I plan on crawling under it tomorrow to see if there is anything obvious.

Misawan · December 1, 2007

I have a 2005 GMC Sierra Crew Cab with only 42000 miles on it (babied) that has decided to start switching itself into four wheel drive (high) by itself. It has done it three times now. I have the button on the dash (2W/4WH/4WL). I have to pull off on the side of the road, shut off my vehicle, then crank it. I can then hit the 2W button and it will switch back in.

Anybody have an idea about this? I plan on crawling under it tomorrow to see if there is anything obvious.

Does yours switch into 4WH or 4WL? I have an 04 Silverado that did this last year. It had been parked all day in a parking lot and when I started it up it was in 4WH and wouldn't switch out. I took it to the dealer and they said that there is a TSB on that and they went ahead and reprogrammed the control unit. That worked for awhile but now in the colder weather it sometimes starts off in 4WH. On rare occaissions it goes into 4WL. Everytime I have been able to switch it back and keep going with no problems. Since it is a "every now and then" problem I can't get the dealer to replace the unit because they can't replicate the problem. It is now more annoying than anything else.

jemurray · December 1, 2007

It switches into 4WH. Today I changed out the transfer case fluid and the front differential fluid. I also had a diagnostic run and it came up clean. I will have to check on that TSB.

Misawan · December 2, 2007

It switches into 4WH. Today I changed out the transfer case fluid and the front differential fluid. I also had a diagnostic run and it came up clean. I will have to check on that TSB.

I did the same thing but it still hasn't gone away completely. I know it is more prone to do it after it has been parked awhile and if the temp outside is cold. I wish I could replicate it at the dealer so maybe they would replace the controller under warranty. So far it hasn't caused any mechanical problems so if there is an upside that is it. Good Luck.

dirtywalter · December 3, 2007

i have a similar problem with my 03 sierra pick up... sometimes after i use the 4wd, switch back into 2wd and then shut the vehicle off and when i get back in the truck, turn it on i am in neutral 4wd... so i put the truck in to neutral "itself" and then i can put it back into 2wd... its a little confusing but its kind of the same problem. so just put the vehicle into neutral and then switch.

jemurray · December 5, 2007

I just got a quote from my dealer for a new encoder motor (located in the transfer case). He is figuring between $400 and $500 just for the part. I know they will charge at least $150-200 for the install. Jeez. To have something like this happen on a 2005 model truck is just wrong. I had it replaced under warranty in June too. The "new" part is supposed to fix this issue once and for all, according to the dealer. I wish GM would just stick with what works instead of trying to save every penny.

Current list of gripes:

-Encoder motor bad at 30k and 44k (one repair under warranty)

-Fuel filter in the tank (now how am I supposed to be able to change that?)

-No transmission plug to drain out fluid before dropping the pan

-No rear differential plug to drain out fluid to replace

Yeah, I am ranting.... Who wouldn't after having to shell out this kind of money on a newish truck during Christmas : |