If it is at pin A of the connector, then reference voltage is correct. Did you have the correct circuit the first time we diagnosed? TCCM replacement was based on this reference circuit voltage being low. Please verify and report back.

What about pin F16 of C1 (light blue) of the TCCM when each of the shift buttons is pressed (nothing disconnected)? Please check and report.

Regards.

Les

 

Yes, this was pin A. Another note, I can sometimes hear a motor on the transfer case trying to run, then sounds like it returns and stops. I don't always hear it but then again our neighbor's damn dog barks non stop when I'm outside so I may be missing it.

Without any buttons pressed it's about 2.2v
Auto 7.4v
2W 3.8v
4xH 4.9v
4xL 2.8v

 

Well this sucks, wife was looking for a new job and got called to work this morning. Looks like I'm going to pull the TCEM off and manually put the T-case in 2wd for now. She needs to use it for work cause I refuse to let her drive my truck lol.

 

I understand your dilemma.

I would disconnect the TC module completely if you remove the shift motor. You will probably need to remove the front driveshaft for clearance to get the motor and electrical connectors off. The rear joint should knock forward off the TC output shaft spline. I tapped it with a plastic coated dead blow hammer and mine popped right off.

FWIW, the voltages being returned from the switch to the TCCM that you reported seem reasonable (I don't have a spec for them). You already verified that the resistance for each of the switch buttons seems good. Just wanted to verify that a reasonable voltage was being returned to the module when buttons were pressed.

Motor running for a little bit - then stopping - then running a bit more....... Mine did this too at one time and it was trying to go somewhere it could not get to - then stopping - then returning to it's original position.

You might want to note if you can click the transfer case through all the positions while you are putting in 2WD, and the effort required to do so.

We can continue when you get a chance. Let us know.

Regards,

Les

 

I got the TCEM out, it did seem to want to 'spring' a bit when the last bolt came out, like it was under tension. I was able to fairly easily change through the gears on the T-case finding the detents. The effort to make the changes felt reasonable to me, easy enough to change with a 6" long wrench. I'm wondering if the TCEM is bad. I'm happy to see that the T-case shifted without a struggle lol, was hoping it wasn't screwed up

 

If anything I would thinka remaining problem might be the position sensor in the motor assembly giving wrong info back to the module (how module knows when it is in a praticular position). There are ways to check, but we can leave that for later. Let us know!

 

I have a 2000 LT with the 4 button NP8 option and was having similar issues with weird shifting into 4WD and the service 4WD light on and after checking everything and replacing the switch I had to make the decision on a new TCCM. I went to my local auto zone and talked to the manager and explained that I wasn't quite sure if replacing the TCCM would make all the issues go away and that I just wanted borrow one to rule it out. He ordered the Dorman model for me and I went back the next day, took mine out of the truck in the parking lot and went inside. He just handed me the new one and said that he knew what I was doing. I went outside plugged it up, took it for a 20 minute ride and to my relief the truck shifts into 4WD just fine and even better no more service 4WD light. I went back to auto zone, thanked them profusely, paid the $218.00 plus tax handed my old one over (no core charge) and now life is good again. Goes to show that sometimes it's not such a bad thing to own a vehicle that tends to have a whole lot of issues.

 

OP in this thread has already replaced the TCCM. We are trying to acertain what else may be malfunctioning.