shawnvw

Do you even have a CHMSL? or is it just cargo lights?
The cargo lights are on the ctsy fuse because it is a ctsy light.....

craigk

Antonia,
It might not be the same problems fix, but I had the same truck in a 1990, W/T series,
It was the same relay you were talking about, If I remember correctley the relay cost about 15 buck back then. I replaced it and the problem was solved, I dont really care why, what,where Or when they made it this way but the relay solved the problem,
good luck.

Antonia

Ok, I'm pretty much home. Should I quit while I'm ahead?

Good idea to eliminate the relay despite my doubts. Autovalue had the relay for 24.00 dollars. There were cheaper 12VDC relays of course, and a 12VDC relay is a 12VDC relay, but I'm really not inclined to swap in another relay/harness/plug since it seems to be any deviation from the norm is usually the culprit in these headaches some way down the road.

I went to the local junk perveyor and got an identical one, from the same spot on the firewall, off of a '90 c1500. Got home, plugged it in, and it commenced buzzing. Oh well. It was a good idea. If anything, it was buzzing more consistantly than my original. Probably sign of a healthy unit!

I removed the CTSY fuse again and got a good strong flashlight up under the dash. (one of a pair of anodized aluminum 9 led flashlights I just picked up at Harbor Frieght in Grand Rapids, MI. 2.99 for the pair with a clipped coupon. Holy crap these are bright!)

So here's what I discovered. There is a terminal block on the firewall straight back of the parking brake. It has about 25 sockets with recessed spade plugs (never know whether to call these male or female. Even electrical systems are getting confused now'days) All were empty, except one. Probably an indication of the simplicity of this 'work truck'. An orange wire was plugged into the top socket of the third row from the left. With a good light on it I could see that the socket had the letters GRN next to it. The sockets are idiot proofed (poka-yoked?) so that you cannot stuff the wrong plug into them. Interestingly, There was a slot on the first row marked ORG that accepted the plug as well. I switch these slots, and plugged the CTSY fuse back in, and presto! Everything works as it did before. Brakes, turn signals, running lights (forgot to check the backup lights). All, unfortunately, except for the courtesy and cargo lamps themselves.

Now the hell did all the outside lamps work for three months with this wire wrong? My courtesy and cargo lamps didn't work before, and they still don't. I was so sure that the CTSY lamp would work now that I fixed someones previous mistake, but they didn't. And all the bulbs are new.

Oh well. I can certainly live without the courtesy and cargo lamps.

Thanks everyone here for your help and suggestions. And for putting up with my ill temper.

EvansBlue

You're welcome.
We certainly don't like tempers, but we certainly acknowledge that its justifiable at times.

66MagicDragon

The 1994 Caviler and Pontiac Sunbird also have the same relay mounted in the same location. Somebody in GM liked that design during those years. As to why the brake lights are tied into the CTSY lights, The original reason was so that if you blew the fuse, you might not notice that you had no brake lights, but you probably would notice that your courtesy lights had quit.
Oh, Also be aware that Advance Auto and Auto Zone have an error in thier databases. If you go in and ask for this relay, they will cross referance to a 5 pin relay instead of the correct 4 pin unit.