2001 jimmy, no 4wd switching, control issues?

06-29-2004, 10:51 AM
I have a jimmy that had a "service 4wd" drive lamp come on last month.
At the time it would come on after driving 10 minutes more or less. It would be off after each car startup. The problem has now moved to an inoperative 4wd hi shift system.

Before I go into my truck further, possibly someone can help with a diagnosis of probable issues? (I have not torn into a car in 15 years... Going slow!)

Here are the Symptoms:

Service 4wd lamp no longer comes on while driving.

Just bought a car OBDII reader (to hook to my computer) and hooked it to the jimmy...No codes present! Well, no service 4wd lamp present now either I guess!

4 hi does not react to button being pressed. (no blinking)

When the tccm fuse WAS unplugged and replugged, all lamps in the 4wd switch set blink. Then it sets into 2hi lamp on, as usual. (good for me)

One time the lamps on the 4dw autotrack were blinking for over a minute. (because I pushed switches in my garage in park?) I unplugged the tccm fuse to try to "reset" the 4wd command to off:
I heard a solenoid click back under the hood.
I had heard the transmission/shift control system disengage too. Motor kind of sound... Mechanical stuff may be working.

At no time will the 4wd hi switch respond now.

Last month when the service lamp was on, I did have intermittent issues with the 4 hi. It had trouble locking in. I didn't even dare to try LOW because I was too far from HOME. It went in 4wd after several attempts, one with a fairly loud clunk. It popped out OK. I was moving the car a little in a parking lot at the time so I can't be sure clunking was a result of improper tire movement.?.

I have seen reference to tech info pointing to varrious items:
TCCM switches, Encoder, Reprograming.

Can anyone help pinpoint where I should start with this problem?


07-08-2004, 12:14 AM
there is a switch in the dash where your emergengy flashers are and is connected to that in some ive had the same prob and replaced that and it worked but that may have been luck too

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