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Blowing fuse

Discussion in '308/328' started by Jdubbya, Mar 22, 2008.

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  1. Jdubbya

    Jdubbya The $10 Trillion Man
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    Dec 28, 2003
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    I decided to check and see why my horn wasn't working (while I had the front of the car apart) and found the fuse was blown. Went to put a new one in and it popped right away. It's the third one in from the passenger side and as far as I can tell controls the horn, cig lighter, emergency light socket, plate lights and key buzzer?

    That's a pretty widely scattered bunch of stuff to start tracing down wires. Is there a way I can tell which one has the short from the plugs at the fuse panel.

    Sorry if this is an elementary question but me and electricity haven't always seen eye to eye. I do have a multi meter and know the basics of how to use it.

    Thanks,
    John
     
  2. miked

    miked Formula Junior

    Feb 7, 2001
    912
    Cincinnati, Ohio
    There is a ton of stuff that runs off that fuse. IIRC, there are 2 connectors @ that fuse and each of those has 2 wires. Try disconnecting one connector and see if it still blows the fuse. That should eliminate half the possibilities.
    Once that is done you could cut one of the wires on the offending connector and retest to isolate the specific wire path. I wouldn't cut the wire except as a last resort but the option is there.
    Most likely there is a dead short somewhere. After determining which connector is at fault try an ohms or continuity test to ground though the connector. You may have to disconnect each device to determine if the short is in the wire or the device itself.
    Good hunting!
     
  3. BillyD

    BillyD Formula 3
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    John,
    I would have said the plate light wire was the culprit as it runs next to the passenger hinge of the engine cover and could easily be shorted but since the fuse pops with the key & lights off I'd guess either the cigar lighter or the emergency light receptacle. Purely a guess though after a couple of beers & without looking at the wiring diagram. Any screws or coins in the lighter assembly?
    Bill
     
  4. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    Note:
    Plate lights (yellow/black) should be on the F fuse (parking lights) not the G (they are labled A-I)
    Also there is a yellow/black wire from the F fuse to the cigarette light for the light -
    It's not the main cig lighter ckt which is yellow/green.
    Temporarily remove the Red (socket) and White/Red (key bzr) and Yellow/Green (cig) wires from G,
    leaving the horn relay powered. Then remove the horn relay.
    If fuse still holds, remove the wires from the horn compressor and replace the relay.
    Press the horn button, listening for the relay to click.
    From there replace the compressor wires (oiling the compressor).
    gl
     
  5. Jdubbya

    Jdubbya The $10 Trillion Man
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    Thanks for the replies gents. I'll try all the suggestions. I should mention that the horn compressor was already disconnected because I had it out. Since I was under the front of the car I pulled it to clean it up anyway. I hooked it up to a 12v source and it works just fine. There's nothing in the lighter Bill so I guess I'll have to start trying each plug to see which one it is.

    As far as the plate lights being on another circuit they may be, I was just going off the fuse list in the owner's manual.

    I hate electrical problems but at least this circuit doesn't power anything too critical!
     
  6. BillyD

    BillyD Formula 3
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    Well, you've had almost a week, any update? With all this snow u can't be out driving!
    Bill
     
  7. Jdubbya

    Jdubbya The $10 Trillion Man
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    No, I've been busy pulling the radiator after apparently poking a hole in it while trying to mount new fans. Once I get that back together I'll get going on the belts and tensioners. If I have time in between I'll try to track down the wiring.

    Isn't this weather crazy? I don't remember it ever snowing this late or this many times in one year. I thought it was supposed to be spring now?? :)
     
  8. Jdubbya

    Jdubbya The $10 Trillion Man
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    Just a quick update to this thread. On a side note, I did get the radiator out and to the shop and it looks like it's re-core time (but I didn't poke a hole in it, it's just shot). Woo-hoo.

    I pulled the connectors from the panel and I do get an ohm to ground reading on one. The only connectors to that fuse on my car are cig lighter (yell/grn stripe) and lamp socket (red) on one plug and seat belt buzzer (white/red stripe) and horn relay (white) on the other (but the plate lights are also listed in the OM as on that circuit??)

    The reading showed on the lamp socket/cig lighter so now I just have to figure out which one it is and find the short. It still wanted to blow the fuse even with the lighter unplugged though so I think I can rule that out. For now I can just leave this plug off and find the short some time down the road. I don't use the lighter or the lamp plug.

    The odd part is that the horn still doesn't work even with a good fuse and the other plug left off.

    I hooked the horn compressor up to a source and it ran just fine. I also checked the horn button and it seems to work just fine. I also switched the relay out with another one but it still didn't work. The relay isn't clicking at all when I push the button.

    Did I say I don't like electrical problems yet?


    Thanks again guys for the help.
     
  9. Jdubbya

    Jdubbya The $10 Trillion Man
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    I hate to post this update but the short is fixed. I had the car at a freinds house so he could so some work on it. He traced it out and it turns out when I put the interior back together I plugged the emergency light socket in wrong so it was grounding to itself causing the short.

    We were also able to trace the horn not working down to the last wire between the plug and the column. Niether of us had the socket to remove the column nut though so that will be fixed later on. At least I know where it's at. Could be a short in the wire or a problem with the slip ring/clock spring or whatever you call it.

    He also figured out the problem with the tach, totally unrelated to this thread but...apparently as I was putting the interior back together (anyone else see a theme here?) when I plugged the tach back in one of the wires pushed out of the back of the plug. He re-seated that wire and put the dash back together voila the tach now works.

    Thanks again Dave!!
     

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