'03 Chevy Blazer -- where's my 4 wheel drive? (UPDATED)

Well, today I fixed yet another problem with my 2003 Chevrolet Blazer -- Friday past, my in-dash 4x4 controls stopped working and hence I could not engage 4 wheel drive. Of course, these things will always happen at the most inconvenient time.

I had to drive to Ottawa, ON (about 5 hours from me) last Friday and, as luck would have it, encountered an ice storm that made driving very treachurous. So, I thought it would be a good idea to engage 4 wheel drive... I pushed the 4 wheel high button and... nothing. No lights on the dash and no 4 wheel drive! What?

I pulled over and checked the fuse -- everything was good there, but I decided to change it just in case. Still nothing. After trying everything I could think of, I just had to deal with it and continue on in 2 wheel drive. Every car I passed in the ditch, I just kept praying my 4 wheel drive would come on... but no such luck. The real pisser here is, I tried it that morning and all was fine... now, when I need it, nothing!

Anyway, skip forward... all went well last weekend, but I still had a broken 4x4 to deal with. And, as if Murphy hasn't already done enough, it's the holiday season and most places are only open a few odd days. That made things difficult when I found out what I needed to look for!

The problem, as I discovered, was corroded wires in the 4x4 module. The module is located behind the kick panel on the passengers side (see picture below). How did I know this? Every time I would engage my 4 wheel drive, I would hear a "click - click" coming from that area... never thought anything of it 'til now! When it stopped working, I went searching... first behind the glove box, but I could clearly see that the only relay (the things that make that "click - click" sound) there was for the signals (turning on the hazard lights confirmed this as you will be able to clearly hear the relay, not to mention feel the click if you put your hand on it).


A shot with the kick panel in place


A shot with the kick panel removed


What we're after -- the TCCM

It only took a few minutes to locate the module and the problem was clearly visible after removing the module from the frame to have a closer look. The wires/plug connector were badly corroded on a few pins -- which led to two broken wires (pin #1, grey w/ black and pin #6, orange).


A shot of the wire harness

OK, so how the heck am I going to fix this? I can only imaging what GM would want to do (read as "harness replacement"... $$$$$$$$$$$$$$). And from asking around about obtaining a replacement plug, my only option would be a scrap yard. Upon talking to a couple yards, they apparently take these modules out ($$$$$$$) and simply cut the connector off and sell it with the module. So, that really only leaves me to a scrap yard that lets you walk around... and haven't removed the module... don't wanna go there. ;)

Plan B... I'll try my local electronics store and see if I can get a few of the female ends (metal clips on the end of each individual wire... there are about 30 wires, I didn't actually count). Again I hit some obstacles. I was told that the clips could probably be found, but they would need a sample to send off. I'll keep looking.

At the last place I tried, I did find a female connector that would do the trick... it just didn't have the tab to hold it in the main connector (each individual wire clips into a spot in the main connector). I thought I'd give it a try and see what I could do (the plastic bag you see in the third image contains a couple more spare connectors in case it ever happens again... I'll know right where they are!).

After cleaning up the corrosion on all remaining wires, and cleaning out the main connector, I stripped and attached new clips to the two broken wires and stuck them in the main connector. OK, now I just need to make sure they don't get pushed out when the connection is made... how? Hmmm... how 'bout hot glue? :) I actually plugged in the main connector to the module (after sealing it all up with dielectric gel... which would have prevented this in the first place) and then inserted the wire into pin #1 and made the connection, and the same for pin #6.

I turned the key in the ignition... Houston, we have ignition! Yahoo! I pushed the 4 wheel high button and heard the familiar sound of the 4x4 module relay and the transfer case motor... wonderful sounds!

So, I have everything working... time for the hot glue. I put a dab of glue down the top of pins #1 and #6 to hold them in place, let it set and tried to pull them out. I was quite pleased when they held, that's for sure! I mounted the module back on the frame, reinstalled the kick panel and my 4x4 was back in business.

Total cost -- twenty cents (a little dielectric gel and about a half hour labour). I'd love to see an invoice for a comparable fix by the Chevrolet dealer!

When I get more time, I'll tell you about all the other things that have gone wrong with my Blazer since the day I drove it off the lot, with 12 KM on it. It is, as so many other blogs I have read from Blazer owners on the web, the story of a lemon.

UPDATE (finally - 07/03/07) -- added images

UPDATE (12/04/07) -- added schematics