when I say a2, the connector is labeled from right to left as I look at it . a, b,c,d so that row I count as a1, b1, c1, d1, therefore, the bottom row again from right to left, a2, b2. c2. d2.

 

right bottom pin is a2

 

I haven't paid much of attention here, but if we're discussing the following diagram of NVG233:
https://blazerforum.com/forum/2nd-ge...70/#post648658
then:

• the illumination led has a separate grounding wire (explanation of the bolded part above)
• a led are constantly "hot" while the strictly ground signal is commutated by the pins of C/D/E to the ground via TCCM module
• to chek out leds (which I doubt they're faulty) You may turn the engine-on to "hot power" them and ground these C/D/E pins to the chassis. They should lit accordingly. For a safety reason while doing that test You may disconnect the plug at tccm, however I don't think it will affect the tccm unit. The diodes seem to have built in resistors for limiting the current flow.
• You may also notice what is the voltage across the C/D/E pins while switching over the drivetrain. For a poor grounding You may see a low voltage drop if the led should be on
• if diodes are ok, then it means there is some problem with either commutation of a ground signal within tccm or the ground wiring at tccm.

Oh, and yes, switch operation has nothing to do with led control, so switch is out of question now.

 

Good input on the LEDs, Mike!

GoJimmygo, I'm having difficulty understanding exactly what you have checked and what you have found by probing the connectors. Can you give me a line-by-line descriptive answer regarding the following 7 power inputs into the TCCM and the 4WD Switch Panel on your 3-button system:

• ATC fuse (hot at all times) feeds TCCM at connector pins D14 and D15 (wire is orange)
• Crank fuse (hot while cranking) feeds TCCM at connector pin D16 (wire is purple)
• BTSI fuse (hot in park/neutral) feeds TCCM at connector pin D2 (wire is light green/black)
• 4WD fuse (hot in run) feeds TCCM at connector pin C8 (wire is brown)
• Courtesy fuse (hot all the time) feeds TCCM at connector pin C6 (wire is orange)
• 4WD fuse (hot in run) feeds Switch Panel at C2 connector pin C (wire is brown)
• Illumination Fuse feeds Switch Panel at C1 connector pin H (wire is grey)

 

I retested all the pins. Everything was accurate as per your above points. C6 had no voltage and as I cleaned the corrosion more the wire came out of the pin. I found it really hard to see the inner corrosion down inside the harness. The green /yellow corrosion covered almost every wire where it goes into the pin. I cleaned it up and with a glue gun reinserted the wire and tested the voltage. All was good so hooked up the TCCM and the 2hi light came on. I pushed the 4 hi and it came on. Then pushed the 4 lo and it came on. Now Its stuck in 4hi????

I went back out and I think its the dash switch now. I had it out and apart a few times, I guess the illumination flickers a little but managed to get it back in 2hi. And the LED,s illuminates to verify. Thanks for all the help Les and all that added to this thread. My ABS is the next issue and will first try to get a dash switch to stop that flickering. When the lights are out, the 4x4 mode doesn't work and won't shift.

 

Sounds like progress has been made!

To me sounds like the problem is still corrosion in the connector to the TCCM. But if you need to replace the dash switch to convince yourself of this, please go ahead - they are relatively inexpensive. You may need to do some sort of replacement on the terminals or the entire connector. Good luck and best wishes.

 

I was thinking about the TCCM connector and almost cut it down to install the loose wire at C6. I have to get a drawing of where the TCCM connector harness goes to and how hard it would be to replace or if I should just splice in the new connector. The dash switch is definitely not 100% and just moving it around while putting it in or taking it out causes the lights to flicker. Its been a long time since the 4x4 mode has been used. I think I will do a fluid change on all the systems to get ready for winter.

 

pretty difficult to replace that wiring as an assembly - it's part of the dash wiring. If you can find a good connector in the junkyard, probably take some wiring with it and then be sure to solder where you connect each wire (shrink tubing would make it a clean install). Just some ideas. If you think the dash switch is on its way out then definitely replace it. Best wishes

 

Thanks for that Les. I called GM . The plug and 6 inches of wiring are $326.00 CDN. Unreal. If anyone has any custom tool ideas and techniques on how to get all the corrosion off these plugs without damaging the wires or pins, it would be a great post. The plastic comb" shaped wire holders that go in the top on each side of the plug, must come out to clean the corrosion fully. That's when the wires are most susceptible to coming out. Trying to remove the corrosion around the circumference of each wire where it is inserted into the pin, was a real challenge. I wonder to disconnect the battery and dipping the whole pin into a solution of vinegar for an hour. Then air dry the pin completely????????? Just a thought

 

If I am remembering correctly (and it has been a LONG TIME since I've dealt with this), I seem to recall the large connector is a 32 pin Delphi Micro-pack 100 series of connectors. This is verified through the pinout I have access to for the NV233 on AllDataDIY.com.

, but keep in mind that you should also pick up to get proper crimps when you install them. Something doesn't look right to me concerning these terminals as displayed on Amazon so I'd like to see a picture from your current connector with the terminal pulled so I can verify that these are the proper terminals for your application.

As far as cleaning what you have, I have successfully unfolded these terminals in the past and hit them with a small brass bristle wheel on my dremel to clean them. A liberal coating of dielectric grease and close them back up. This has worked for me, but I have also had some that were so far gone that they just broke up while disengaging them from the connector body. My preference ever since is to try to have replacement terminals on hand before I start one of those jobs.