I got a hold of a Tech2 yesterday

The TCCM did not show up anywhere in the diag.

I'll start chasing the grounds. I'm working off of a few GM wiring diagrams. I'll post the results

 

Sidenote, what ever happened with the trans I sold you? Curious what was going on inside

 

I took it apart and it sat for a while . . . and it is still sittin in buckets

There's a few steels that have hot spots. For the most part it was clean, but there was some clutch material in the valve body.

I bought a full convertible 73 K5 blazer. I'm putting my iron 6.2, your old rebuilt 80e and a 241c tcase in it. If all goes well, I have a rebuilt CTSV blower that will go in also.
It's by no means a mud truck. It's not going to be like my 92 that I had. I have two kids that enjoy it more than I do, so it needs to be kid friendly.

 

highly disappointed

Just replaced the transfer case harness the original was looking rough . . .

still nothing

 

I'm currently having similar problems, tcase not shifting, lights not working anymore. I still need to change the encoder motor, but I found the ground under the drivers area, towards the outside of the frame rail, on a tab is a ground, after I sanded and cleaned it chasing an abs issue, the switch lights up better now.

 

what about the actual tcm behind the cluster? Mine is have similar issue. I tried the scan tool and it would not connect at all

 

Hi:

This is my first post, be gentle.

I fought 4WD engagement issues on my 2003 3/4 ton Suburban for months. It is really hard to diagnose without a Tech 2. You are lucky that you had access to one.

I think you've got a power (or ground) problem for the switches or TCCM. In all the experiments I did, I never saw the dash lights go out unless I had pulled one of the 4WD fuses (4WD on dashboard or TREC under the hood).



TREC fuse under hood 2003 Suburban K2500. From 4wdhelp.com



Can you verify power to the buttons? I'm surprised they don't light. Can you verify power to the TCCM? Not showing up on Tech 2 seems odd. Also, 1.8V at the transfer case seems very low. Unless you just meant the diagnostic voltage sent out by the encoder wheel in the transfer case actuator.

Do you get the "Service 4WD" message on the control panel? Right at start up or after you try to push some buttons?

Are you interested in just putting the transfer case in 2WD manually and disabling the Auto Trac for now? Or is that not helpful to you? You probably know how already, but you'll have to get the encoder motor and transfer case input shaft forced to 2WD mode, then unplug everything so that it does not move on its own.

My problem was different than yours. It turned out I had an almost broken ground to the front axle actuator. The voltage would show up at about 10 or 11 V (instead of 12-13 with engine off), but when I actuated the 4WD, it could not actually move the axle actuator. It just made a humming noise. If I had chased that problem down earlier, it would have saved a lot of time and money.

Since all this was such a PITA, I started putting together a web site to gather what I'd learned and help people diagnose their own problems. Link is in my signature below. Please let me know if you find useful wiring diagrams. I want to add more of those to the site.

 

thanks for your suggestions, I'll read up more tonight.

No there is no current message being displayed on the dash.
The buttons are still "powerless" but I do have voltage at it.
There is voltage at the actuator also.

It's currently in 2wd, or 4wd. I put the old actuator back in so that it could be driven.

I did redo the ground connections at the frame recently.