Hello - brand new member and new to the FD scene. Bought a beautiful 1994 Montego and am looking to sort out a few issues to get it through state inspection. One issue is the seatbelt light / airbag lights are flashing on the dash. Thanks to this fantastic site, I pulled out the CPU2 board and, sure enough, there seems to be some suspect around capacitor 02. I'm more of a software guy than hardware, but it looks like a leaky capacitor. Wanted a second set of eyes. Also, (1) are there any schematics around for this thing and (2) is anyone refurbing these and selling the boards?

Thanks in advance!

 

Not an FD guy myself but I do have some electrical experience. It looks like there’s some kind of residue on the board either from the capacitor or some corrosion. I’d clean the board down as best you can and replace the capacitor and 2 surrounding resistors in case the damage caused a short somewhere in there. It doesn’t look like trace damage at first glance but if you brush off the residue and see exposed copper, it’s bad news for that board.

TLDR: Clean the board, check for damage, then replace the 10uf capacitor and resistors (look up how to read resistors if unsure of resistance).

Hope that helps!

 

Yep, that is damage on the board. But I see more that needs fixing than the capacitor and the resistors around the capacitor. Look at the resistor above the label R19 - do you see the cracked solder on it? I would replace that one or at least repair the solder. The resistor labeled with 29 to the right of it also looks suspect. In fact, there are a number of issues with the board cleaning it may resolve a bunch.

If you post up shots of the entire board, I am sure Gen2n3 will be able to assist. FYI - it's not too difficult to repair the board if you have some simple soldering skills. I'd also invest in some desoldering braid to help.

 

Thank you! The brown residue cleaned off well with rubbing alcohol. Ordered a few capacitors and resistors for the surrounding area and will try to get it cleaned up and new solder joints done.

 

Hello - follow-up post here. Pops has worked - on the side - in electronics repair on and off for the past 25 years so I took the board over and we found that CAP02 was indeed faulty, the one that had leaked onto the board. The resistors surrounding were giving a "normal reading" according to the limited testing he did. I reassembled and tested...unfortunately the problems persist -

1. Seatbelt blinking light with belt buckled - this one seems most likely like it should've been related to the board.
2. Solid airbag light
3. Click-click start issue - so annoying

Any other reset that needs done after this board is replaced? (battery was disconnected)

From my reading on the forums, these could be related to the board, or otherwise. Help me decide what I should tackle next.

Thanks so much!

 

The seatbelt warning is definitely the CPU. The airbag is a whole different circuit and the airbag system has its own computer.

Also the click-click-start issue doesn't relate to the CPU. There's a large thread on it, sometimes it's the starter cut relay that needs to be bypassed. Sometimes getting a starter booster relay helps a lot, Banzai Racing has a kit. IMHO the starter booster is a great way to go, that solves most of the click-click-start problems.

Dale

 

Click-click-start gremlins are most definitely tied to CPU2. The security relay runs through that unit, which is the usual culprit. If I'm not mistaken, the seatbelt circuitry is part of that CPU as well. Note: Two birds w one stone if you are able to fix yours.

Props on trying to improve the electrical board yourself. If unable to effectively refurbish, you should still be able to get a new CPU from a 3rd party online supplier; $250-ish or so as last I recall. Or you can try some of the numerous bandaid fixes mentioned above.

The air bag solid light is likely attributed to a completely separate diagnostic module. Unfortunately, those units are hard to come by in good shape used (but doable); definitely out of luck getting brand new.

 

Thanks all. I sincerely appreciate the willingness to help out. This FD is so nice and I want to do it right if I can. I didn't mention it earlier, but the car also has an aftermarket security system.

Outside of new, are there any online services, etc. That refurb the board? any other diagnostic strategies from anyone outside of visual inspection?

 

CPU 2 from Ray is ~$270 shipped right now. If you post more pictures of your board(s) people more experienced with PCB stuff could probably help you identify other things that could be wrong with it.

I am not sure if it was mentioned or even relevant, but you may want to check the seatbelt sensor where it plugs in under the driver's seat and just make sure everything looks good. Otherwise it does sound like a CPU 2 issue. I am sure most remaining electronic repair shops could refurbish the CPU 2 board, but honestly it may not be cheaper than a new board unless you do it yourself.

Regarding the airbag module your only choices are to repair or replace with a good used unit. Solid airbag light means either the module is not plugged in, or it has an internal fault. I would open it up and look at the board. If you are "lucky", its just the fuse resistor burnt out from the long-term existence of another error. Otherwise it could be the capacitors or any of the other usual suspects. Finding a shop to refurb this one might be tricky, I have a feeling many companies will walk away due to liability since it controls the airbag system.