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Electrical Gremlin

Discussion in '308/328' started by PDB, Jul 21, 2016.

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  1. PDB

    PDB Formula Junior

    Feb 1, 2011
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    Paul
    #1 PDB, Jul 21, 2016
    I've been trying to trace a fault that is causing the RH dippped headlight not to work and whilst sitting in the car with the ignition on, but with the engine not running, I discovered a rather odd situation.
    If the headlights are turned on and I turn on either turn signal/indicator, the speedo swings wildly from stop to stop and the mileometer clocks up miles!! Any ideas?

    Paul
     
  2. MNExotics

    MNExotics F1 Rookie
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    Ben Gruenzner
    #2 MNExotics, Jul 21, 2016
    You are going to have to chase the wiring. Either it is wired wrong or thee is bleeding in the circuit.
     
  3. PDB

    PDB Formula Junior

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    #3 PDB, Jul 21, 2016
    Bizarrely, after I ran the engine for a short period and then turned it off, the problem disappeared.
    Is there any possibility that the position of the engine e.g. ignition, points etc. could have caused the issue?
     
  4. Doubleodan

    Doubleodan Rookie

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    #4 Doubleodan, Jul 21, 2016
    I think the ignition circuit is far enough removed that the engine/points position would not be relevant. I would look for a bad ground or loose connection first. A bad ground can send stray voltage elsewhere (per MNEx-bleeding) to complete a circuit and can cause sensitive items (speedo) to act funny. If the problem happens again, see if you can wiggle (carefully) the harness near the headlamp and work back. You may get lucky and find an area that is affected by the wiggling. It doesn't always work but I have numerous times found loose connections that would have taken me more time to trace. Also, it sounds trivial but I always clean battery terminals and ensure good battery voltage before starting electrical work. Maybe it will just never come back!


    Sent from my iPhone using Tapatalk
     
  5. GordonC

    GordonC F1 Rookie
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    #5 GordonC, Jul 21, 2016
    Without having a clue which circuit might be involved, you might want to check the relays also - perhaps a sticking relay could cause a bad circuit to the dash?
     
  6. pad

    pad Formula 3

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    Paul Delatush
    #6 pad, Jul 21, 2016
    Especially with these cars, the first step in chasing electrical problems starts with servicing
    ALL the ground points, including the quick connect located near the left headlight. Good luck hunting.
     
  7. PDB

    PDB Formula Junior

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    #7 PDB, Jul 22, 2016
    That's good useful information. I wasn't aware of the connector that you referred to.

    Thank you.
    Paul
     
  8. Ferraridoc

    Ferraridoc F1 World Champ
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    #8 Ferraridoc, Jul 22, 2016
    That's a bad earth until proven otherwise. When you use an adjacent circuit the current will go backwards through the speedo, in this case. Check all your connectors and earths.
     
  9. PDB

    PDB Formula Junior

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    #9 PDB, Jul 23, 2016
    Will do, thanks.

    Paul
     
  10. PDB

    PDB Formula Junior

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    #10 PDB, Jul 24, 2016
    I now have working headlights again, so thank you everyone for your advice. I don't know precisely which connection it was, but I disconnected and cleaned all of them.

    Still don't have working fog lights though.

    Paul
     
  11. Ferraridoc

    Ferraridoc F1 World Champ
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    #11 Ferraridoc, Jul 24, 2016
    Start at the relay
     

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