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    Old cars, old capacitors and new problems

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    • Old Busted Hotness
      Old Busted Hotness last edited by Old Busted Hotness

      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:

      alt text

      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.

      alt text

      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:

      alt text

      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.

      alt text

      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.

      alt text

      There's one now, in the EFI control module. GET IT, before it bites ya!

      e90m3 WhoIsTheLeader AkioOhtori 3 Replies Last reply Reply Quote 9
      • e90m3
        e90m3 @Old Busted Hotness last edited by

        @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.

        Old Busted Hotness 1 Reply Last reply Reply Quote 4
        • Old Busted Hotness
          Old Busted Hotness @e90m3 last edited by

          @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!

          1 Reply Last reply Reply Quote 1
          • WhoIsTheLeader
            WhoIsTheLeader @Old Busted Hotness last edited by

            @old-busted-hotness Congratulations! Troubleshooting old electrics rarely doesn't also break something else.

            1 Reply Last reply Reply Quote 2
            • AkioOhtori
              AkioOhtori @Old Busted Hotness last edited by AkioOhtori

              @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?

              Old Busted Hotness e90m3 facw 3 Replies Last reply Reply Quote 1
              • Old Busted Hotness
                Old Busted Hotness @AkioOhtori last edited by

                @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.

                1 Reply Last reply Reply Quote 3
                • e90m3
                  e90m3 @AkioOhtori last edited by

                  @akioohtori I'm a process engineer for a capacitor manufacturer.

                  AkioOhtori 1 Reply Last reply Reply Quote 5
                  • AkioOhtori
                    AkioOhtori @e90m3 last edited by

                    @e90m3 Now that is a factory tour I'd pay to take.

                    sn4cktimes 1 Reply Last reply Reply Quote 4
                    • facw
                      facw @AkioOhtori last edited by

                      @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).

                      1 Reply Last reply Reply Quote 0
                      • sn4cktimes
                        sn4cktimes @AkioOhtori last edited by

                        The breadth of knowledge on this site is often truly staggering.

                        1 Reply Last reply Reply Quote 3
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