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Intermittent Electrical

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    #1

    Intermittent Electrical

    Hey all-
    I've got a 93 sedan F22A1 - which I just recently got back on the road after buying it a couple of months ago.

    Very intermittently, the electrical power goes completely dead. I mean, no dome light, no idiot lights, absolutely nothing electrical even attempts to function.

    Previous owner recently replaced the alternator...it was still new-ish when I bought it. 2 weeks a go noticed it was cranking very slowly. Checked alt when running & it's showing about 13.5v. Brought battery to AutoZone - it tested @ 2% of capacity so I replaced it. I figure the battery was drained flat a few times before the previous owner replaced the alternator & the battery was damaged...so I didn't think much of it.

    On 4 occasions now it has done this Electrical DOA thing. During one episode I put my DVM across the battery & measured 12.6V. I then put my negative lead on a chassis bolt & measured the same 12.6V (purpose of this test was to verify that the ground connection was good). Then I put my neg probe on the chassis bolt, and positive on both sides of the battery main fuse in the underhood fuse box...same 12.6v on both sides - so the connection to the fuse box is good and the fuse itself is good..

    Still, in that state - with good power to the fuse box, no power anywhere.

    I walked into the house, then back to the car to get in...noticed the dome light was now working. Idiot lights came on when I put the key in. Started right up with a nice fast crank.

    The car acted normal for 3 days after that episode. Now today my daughter got in it & drove to school. Upon getting out at school, she went to unlock the pwr doors...no juice. Completely dead again. It drove fine...but after it was shut off, it's as if the battery is completely disconnected...except that based on my testing, the connection to the fuse box is good.

    Unfortunately I'll have to wait until I get the car back tonight to repeat my checks...meanwhile, I'm hoping the car magically heals itself so I don't have to go rescue it.

    Any ideas?
    Tags: None
    #2
    Originally posted by 2Sheds_Jackson View Post
    Hey all-
    I've got a 93 sedan F22A1 - which I just recently got back on the road after buying it a couple of months ago.

    Very intermittently, the electrical power goes completely dead. I mean, no dome light, no idiot lights, absolutely nothing electrical even attempts to function.

    Previous owner recently replaced the alternator...it was still new-ish when I bought it. 2 weeks a go noticed it was cranking very slowly. Checked alt when running & it's showing about 13.5v. Brought battery to AutoZone - it tested @ 2% of capacity so I replaced it. I figure the battery was drained flat a few times before the previous owner replaced the alternator & the battery was damaged...so I didn't think much of it.

    On 4 occasions now it has done this Electrical DOA thing. During one episode I put my DVM across the battery & measured 12.6V. I then put my negative lead on a chassis bolt & measured the same 12.6V (purpose of this test was to verify that the ground connection was good). Then I put my neg probe on the chassis bolt, and positive on both sides of the battery main fuse in the underhood fuse box...same 12.6v on both sides - so the connection to the fuse box is good and the fuse itself is good..

    Still, in that state - with good power to the fuse box, no power anywhere.

    I walked into the house, then back to the car to get in...noticed the dome light was now working. Idiot lights came on when I put the key in. Started right up with a nice fast crank.

    The car acted normal for 3 days after that episode. Now today my daughter got in it & drove to school. Upon getting out at school, she went to unlock the pwr doors...no juice. Completely dead again. It drove fine...but after it was shut off, it's as if the battery is completely disconnected...except that based on my testing, the connection to the fuse box is good.

    Unfortunately I'll have to wait until I get the car back tonight to repeat my checks...meanwhile, I'm hoping the car magically heals itself so I don't have to go rescue it.

    Any ideas?
    The ALT showing 13.5V doesn't seem correct. I know they should be 13.6V - 14.6V but all good ALTs I've seen were 14.6V. But this doesn't explain the root cause.

    The root cause is that you have a power drain in the system somewhere. You will need to check for resistance in wiring from point A to point B to try and narrow down what is draining the battery when the car is off. OR, what item is staying on when you shut the car off. Some examples:

    - Dome light stays on when you leave the car as the door latch to tell it to shut off is broken
    - After market stereo installs not wired properly
    - After market alarms not installed properly
    - Antenna that does not go down all the way (and keeps trying)
    - Any light that stays on due to a short
    - Bad grounds
    - etc.

    Eric can show you how to use your multimeter in-line with the cars ground to find the parasitic draw on the battery. Good luck!
    http://www.ericthecarguy.com/faq/sol...oblems?start=3

    Comment

      #3
      I hear what you're saying - I used a similar technique to find a sticky relay causing my fuel pump to stay "on" in my old VW Passat. But this is different...in case I wasn't clear in my post...even while the rest of the car is dead, the battery is fully charged.

      It tests good all the way to the fuse box. The car acts as if the battery is disconnected - not even an LED dome light, which draws virtually nothing, will work. Then a minute later, everything works perfectly and the battery will crank the starter all day if I wanted to. So it's a battery disconnected issue vs a battery drain issue.

      I guess at this point I'll have to check the fuse box for continuity since it's acting like an electronic roach motel - electrons check in, but they don't check out lol

      Comment

        #4
        When the power "goes out" again, check the voltage on your interior fuse box. Just probe around and see if you get a reading.

        Check for voltage at fuse #22 underhood box, that carries power to your dash fb.

        Check ground M as well, right side of dash in the kick panel I believe.

        YouTube Clicky!!

        Comment

          #5
          Crap my daughter just called - when she got in it, it acted normal...idiot lights OK, dome light OK, green ring around the key. The instant she went to turn the key, everything went black.

          Messing with the ignition switch did no good.

          But, as I talked her through some troubleshooting, we find that everything is 100% dead (not dim, but totally out) except the hazard lights. The front, rear and the arrows in the dash are all nice and bright. Crazy. So I'm mounting a rescue mission now...should be fun lol

          Comment

            #6
            The hazard switch is a direct connection to the lights so it doesn't count.

            YouTube Clicky!!

            Comment

              #7
              Fixed! Sometimes the stars align just right & things work out.

              I got up to her college campus at about 8PM, found the car in the darkened lot...sure enough it was stone dead. Except of course for those hazards, which worked fine.

              I left the driver's door open and went out to open the hood. I tapped on the battery master fuse - and I saw a tiny spark...at that instant the dome light flickered. I tapped it again...another spark, another flicker.

              Disconnected the battery - unscrewed the fuse - which has a copper tab on either side of it (it's not like a normal automotive fuse) and each tab is secured by a screw. One of the screws was tight, the other was pretty loose and the copper tab that went under it was just about obliterated. It must have been making intermittent contact under full load & the arcing just destroyed the metal. Fuse was still good, but was really only attached on the load side.

              Anyway - I managed to move it over a bit so the screw could grab a decent amount of metal for good contact, and it fixed the issue. I'll replace the thing tomorrow - but if it hadn't been dark outside so I could see that tiny spark and notice the dome light come on, I'd probably still be messing with it.
              Last edited by 2Sheds_Jackson; 02-12-2015, 10:23 AM.

              Comment

                #8
                Originally posted by 2Sheds_Jackson View Post
                Fixed! Sometimes the stars align just right & things work out.

                I got up to her college campus at about 8PM, found the car in the darkened lot...sure enough it was stone dead. Except of course for those hazards, which worked fine.

                I left the driver's door open and went out to open the hood. I tapped on the battery master fuse - and I saw a tiny spark...at that instant the dome light flickered. I tapped it again...another spark, another flicker.

                Disconnected the battery - unscrewed the fuse - which has a copper tab on either side of it (it's not like a normal automotive fuse) and each tab is secured by a screw. One of the screws was tight, the other was pretty loose and the copper tab that went under it was just about obliterated. It must have been making intermittent contact under full load & the arcing just destroyed the metal. Fuse was still good, but was really only attached on the load side.

                Anyway - I managed to move it over a bit so the screw could grab a decent amount of metal for good contact, and it fixed the issue. I'll replace the thing tomorrow - but if it hadn't been dark outside so I could see that tiny spark and notice the dome light come on, I'd probably still be messing with it.
                WOW!! Glad you were able to find the ghost steeling your voltage!! I'm terrified of electrical problems since they can really become a disaster!! Good Luck with her man!!

                Comment

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