I've got a '90 vert and the cpu has gradually started to
fail. Looking at it, I see a resistor which supplies power to the unit has failed - probably slowly, so the rest of the unit is probably good. But in failing, it burnt off all the colors which would allow me to replace it.

If someone has a cpu they can look at, the resistor is one of two that stick up from (instead of laying along)
the board. It's about .5" below the relay and just to the left of an electrolytic capacitor. It's marked 'R1' on the board.

If you could read the colors/resistance from your unburnt resistor, I will have much to give thanks for
during the upcoming holiday!

Thanks,
Cyrus

 

cpu or ecu? If its CPU I will take a look at it tomorrow morning.

 

CPU, not the ECU. As in, one electrical system after the next starts to fail, from the alarm to the warning buzzer to the seat belt lights, etc., which is a little discouraging until you realize the CPU runs them all.

Thanks,
Cyrus

 

My 86 GXL has been having similar problems, i was guessing maybe the solder connections.
Though my seatbelt light doesnt work at all. and the alarm sometimes works if i open then close the hatch.

Anyways, thanks for the idea! i'll have to look at the CPU on mine and see if there's any visible problems!

 

hey cxr,
just posting because you are the first person I've seen in a long time with my name and exact spelling

sorry i can't help
good luck

-Cyrus

 

I'll check later this morning for you on a FC66 CPU.

BTW, the 90-91 US spec convertibles use a different CPU than any of the other cars.

 

I have a 90 'vert, I know the ecu's are different from any other n/a model, I'm not sure if the cpu's are the same though. I can look at it right now if I can find it (mine's on blocks waiting for me to rip out the engine anyway)

 

oops, icemark allready made the remark about the cpu's being different. d'oh. I need to read closer...

 

hey, I took the kickpanel off, took a look at the cpu, I have no clue on how to remove it. How'd you do it? the dead pedal is in the way, and some sheet metal.

 

There's a detailed description of how to remove it, with pictures, here:

http://www.teamfc3s.org/faq/

After you take it out, take the plastic cover off, and the large board (there are two smaller ones) is the main CPU board!

 

10mm nut on top, remove that. Pop the top edge of the CPU out over the mounting bolt, then slide the whole thing up. There is a tab on the CPU that holds the bottom in.

 

I have a 91, I will check it as soon as possible. Hope I can help.

 

hehe, thanks icemark, you make it sound so easy. I dunno what the previous owner did, but mine sure as hell doesn't look like that picture. The cpu and fuse box are there, but my cruise control is way over somewhere else. And there is a lot of very stiff wires that are in the way. Sorry, I'm not going to bother, it's going to require me to remove a LOT of things there to get at the cpu.

 

Ok took a look off my 90GTU cpu, R1 is a 3.3 Ohm +/- %5 resistor. Color code Orange Orange Gold Gold. Hope that helps.

 

the gtu and vert have different cpu's, that resistor may not be the same.

edit: forgot key word: resistor, lol

 

The scematics are basicly the same.. especial for first few resistors and capisitors. So I am pretty sure they are the same.. but I could be wrong.

 

I've just finished adding a 2.2 + 1.0 in series, to help dissipate heat, and it's fixed! Hi-beams, warning buzzers, etc. are operational again.

The resistor delivered power to a transistor that was gated by a zener, whose output powered the cpu chip. As it failed the voltage dropped and the chip gradually became inoperational. I was getting alarmed as one thing after another failed, until I realized there was a common point of failure.

Thanks very much for looking for me! I owe you dinner if you ever make it to NC.

Cyrus

 

well looks like you were right trainwreck. my apologies.

 

Convertibles have the cruise brain over by the ECU.

 

Your welcome sir.