Howdy folks, so a short while ago an odd problem with my 4x4 control popped up, and I'm really not sure how to even begin diagnosing it. It's a 4 button one.

so here's what's going on.
You know how when you first start the vehicle and the kickbox /control computer fires and all the lights on the controller briefly flash? It does that randomly all the time, driving or in park. I'll hear two quick firings of the kickbox, everything flashes, then it returns to normal.... except sometimes it doesn't for a minute or two, during that time all the lights will be illuminated and flickering like crazy- it's like the system isn't grounded properly.

I pulled the kickbox out and checked the pins, there was some minor corrosion on the power pin, but I cleaned all that up and it didn't correct the issue.

Is it possible the power supply/inverter on the kickbox itself has begun to fail? Where does this system ground? Where could I check the power upstream?

Appreciate all your thoughts on this, I'm thoroughly stumped.

 

When you say "kickbox" are you referring to the transfer case control module, the TCCM, that lives behind the passenger side kick-panel?

If so, a common issue with these is the relays start not working well. What will happen is that they start clicking repeatedly instead of just the one time necessary to switch the transfer case to the new configuration.

Some people have had success with getting rid of the corrosion. However, most just replace the TCCM.

 

Oh my mistake, yes I mean the TCCM. 😅
Definitely thought kickbox was the proper colloquialism for it...

I'm not convinced its solely the relays failing. The way it cycles on and off or gets stuck flickering like crazy really has me believing it's a power or ground issue.

I canceled my all data subscription some time ago, but maybe I should buy another month 🤔? I need circuit schematics for the TCCM so I can trace the power and ground - if that fails I'll hunt for a used TCCM and just switch them out.

 

If you could figure out how to repair a TCCM, I'm sure others would want to see how you did it.

I have the GM Service Manuals for my 99. Would they have the schematics you need? I could scan and post the pertinent pages as long as you promse to report back with any success you have making the repair.

 

Well AllData wouldn't even let me preview their listings to see if they even had what I'm looking for, so they don't get my 20$ 🙄....

However, I don't think you'll have to scan anything for me. I believe I found everything I'm looking for in these two threads:

https://blazerforum.com/forum/2nd-ge...-blazer-89044/

and

https://blazerforum.com/forum/2nd-ge...diagram-94462/

Which got me the power+ ground diagram and the pinout diagram to cross reference to.






The only thing I'm not certain of is how to read what the expected voltages/amperage of the circuits are supposed to be, so even though now I know where to look - I still dont know what to look for :/

If it is the TCCM itself that's going bad, I've had alot of luck reviving electronics by briefly baking them for 5 minutes at 450f in the oven. So maybe that'll work here 🤷‍♀️?

 

Ok. Looks like you have all the info I could possibly provide.

And yes, it is not always obvious what voltages are used in the circuits. I believe logic circuits run on 5V but that is a guess.

I can see how baking the circuit board could work as it would reflow the solder and repair those connections.