I have a 1993 Chevy G20 Conversion van, 177k, 5.7 V8. Runs great for the mileage.

A couple of months ago, the DW called when she was leaving from a friends and said the Electric Windows wouldn't work, the Speedometer wasn't working, the AC/Heat Fans weren't working and the ABS light was on. I had no clue where to start, but figured something in common was causing this. Drove over and then drove the 5 long miles back as the transmission was put in 'limp home' mode. While driving it home, the SES light came on and the code was that it couldn't sense the speed.

I got it home, checked the fuses and everything seemed to be fine. I managed to wiggle this big black module at the bottom of the fuse block and for some reason everything came back to life. This happened a couple of times over the past few months and each time, my remedy was to jiggle this black module.

Well this happened again this weekend and no matter how much I jiggle the black module, I can't fix the problem. It does have a number on it, GM has discontinued it, not available anywhere. I wrote the manufacturer and they say that that module is just a tone alarm and has nothing to do with my issues. I did manage to take it apart and determine that some moisture had caused a little rust/corrosion on the inside.

So, if it's not this module, what would cause all of the above to quit working at the same time and is somehow connected at the fuse block?

Danny

Your probablynot going to like it but it sounds like typical fuse box corrosion. The fuse panel is mounted to the firewall and on the under hood side it attached to the wiring harness by one bolt in the middle of the block. Remove the center bolt and pull the harness off. Don't worry it won't fall apart. Look for corrosion where the connectors plug in.
If the harness or fuse block are corroded you might end up bypassing the blockand running a jumper wire through the firewall.

I took that fuse block apart yesterday before actually reading your post, having traced it to possibly being there. It was a little late in the day, so I didn't see any corrosion but will take a look at it in better light. It looked to be clean but will know more later.

I do know that on the fuse block inside, I can use my meter and do know that there is one vertical row that does not seem to be getting power so this tells me that either that fuse block is suspect or there is an issue with a fuseable link.

Danny

Still fighting this bug. Here's what I know. Took the fuse block apart and sprayed it with electrical cleaner and used a points file to make sure the sockets were clean of corrosion. I didn't see any present on the inside or outside. I re-assembled it and of course tried it again with the same results of the various items not working.

I got my meter out and began checking fuses and connections. I am not getting power to the fuses that control the items that aren't working. Thinking that it might be a fusible link, I then took them from the distribution area inside the engine compartment and traced them 1 by 1 to the point where they enter the fuse block and the 2 that go directly there provide power to the fuse block as expected. I have no idea where the other 2 go.

So, I suppose the question is, where else would you look to find where power is provided in 1 place to all of these elements? I'm still tracing things, but not having luck so far.

danny