Old cars, old capacitors and new problems
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Chances are, if you're running an old car you're gonna have some buggy electronics at some point. Well, not if you car's really old, but medium-old like my 1988 LTD Crown Vic.
30 years is about when capacitors start to decide they've had enough and retire from active service, and that causes annoying, buggy behavior, like this:
That little ring around the lock is... half illuminated, when it's supposed to be dark. This is caused by, you guessed it, a bad capacitor, this time in the illuminated-entry module.
It's the little black box there above the ground bus. You'll need a factory service manual to find it, because Ford hides these things all over the place. In a Fox Mustang it's under the rear parcel shelf.
Its job is to light up the lock rings and interior lights for 25 seconds when you lift the handle with the door locked. This is so you can find the keyhole in the dark, or just look inside to see if there's anything worth stealing in the car.
The module itself opens from the end, and the circuit board slides out:
The capacitor in question is the little yellow can on the RH side. Mark which side is negative (stripe on the can) and replace it. Easy job if you're solder-savvy, 5 minutes at most. The orange discs are also capacitors, but those don't go bad.
In this case it's a 10uF 25V capacitor. You can replace with higher voltage without affecting performance. If you're like me (1) God help ya and (2) you've probably got capacitors laying around.
Inspect the contacts on the relay and clean/polish if needed.
Test and reinstall, in that order. In my case, the capacitor did the job.
Now everything lights up for 25 seconds and then goes back to sleep, as it should. RESULT!
There are other capacitors, and they'll be just as bad.
There's one now, in the EFI control module. GET IT, before it bites ya!
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@old-busted-hotness said in Old cars, old capacitors and new problems:
you've probably got capacitors laying around
I make capacitors, so I've got a few lying around.
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@e90m3 said in Old cars, old capacitors and new problems:
I make capacitors, so I've got a few lying around.
Send me some, I've almost used up my stash!
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@old-busted-hotness Congratulations! Troubleshooting old electrics rarely doesn't also break something else.
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@old-busted-hotness Also (I want to say) early 2000s there was some huge electrolytic capacitor manufacturing problem. I don't recall (ha!) any of the specifics, but the tl;dr is all capacitors of that era are suspect. Just another part of the "fun".
@e90m3 wat?
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@akioohtori And early 2000s cars will have a whole lot more of 'em. Happy hunting, y'all!
I should add that if you don't have the exact capacitor you need, you can add them in parallel. Two 4.7s or three 3.3s will do the same job as a 10.
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@akioohtori I'm a process engineer for a capacitor manufacturer.
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@e90m3 Now that is a factory tour I'd pay to take.
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@akioohtori Ah yes, that was good fun (more mid-'00s I think?) Ether way, in the PC space you still see motherboard makers advertising that they use solid or Japanese capacitors due to the lack of trust that created. Personally I've lost at least two motherboards, two monitors, and a TV to capacitor issues (all were obsolete enough that I didn't bother to try replacing).
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