99 Jimmy - 4wd problem

[cpfeifer]

I have a '99 GMC Jimmy 4x4. My 4WD was not working. The light would flash but not engage. I took it to a transmission shop who changed the motor in the transfer case. The problem is the 4WD lights on the dash do not light and the Service 4WD light now appears. The transmission shop said there is power to the motor, but they can't figure out how to get the 4WD lights to work - or to engage. They suggested going to a dealer who might have a "tech 2 diagnostic scanner" which could figure out the problem, but I am reluctant to go to a dealer and get raked over the $$$$ coals. Has anyone seen this - if so, suggestions on how to fix it?? Thanks!!

[MT-2500]

Fuse???
Well you have done been raked over the coals.
You have done be had by the trans shop if they did not have the proper test equipment to test it.
Find a good dealer or quailfied repair shop to check it out.
Or get it scanned on a good engine trans capable scanner and post back codes and someone will help.
MT

[photohawk58]

To; MT

I have the same as cpfeifer. I did chech all the fuses, the switch in th dash has been changed, still won't light. I had it scanned with some kind of hand scanner. The mechanic said he got a code: P0315, claimed it ment "open ground", Performed diagnostic trouble code check, recommended replacing the Transmission Control Module, GM's price $444. Oh, by the way they tell me GM also use 3 different types of transfer cases in the 99; they tell me I havea NP8.
Here is my problem, I have another mechanic say you can not scan the 4WD, He also said ther is no such Code as P0315 for the 4wD. Can anyone untangle this mess? any help will really be appreciated by me and I am sure cpfeifer. It does seem very strang 2 vehicles with the same symtoms.
It is winter here in the Northeast and We need the 4W. I am very upset becasue I just got threw with an major intake leak problem, which cost big bucks when I got threw with the Dealer.
Thanks,
Photohawk

[MT-2500]

Photohawk58
The first mechanic was right on tract.
The electric shift transfer case is a New Venture 236

http://members.troublecodes.net/crunch/315.pdf

Code P0315 is a shift mt ground circuit problem
Read the pdf. link I posted if no open in ground wire then you replace the ATC control module
MT

[snowmanjoe]

I had the same problem with my 2001 Jimmy. The 4wd light would flash continuously and not engage. The ATC control module shorted out some how. The dealer couldn't explain why. Replacing the ATC control module fixed it.