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Strange Headlight Lift Motor Problem

Discussion in 'Technical Q&A' started by fiatbrett, Nov 11, 2011.

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  1. fiatbrett

    fiatbrett Karting

    Aug 20, 2009
    98
    Tallahassee, Florida
    Full Name:
    Brett B
    #1 fiatbrett, Nov 11, 2011
    My headlight switch is sketchy already as I have to find the sweet spot between the full "on" and "off" positions on the stalk to get them to pop up. The car is an '85 308 QV.

    So I was doing this routine tonight to get the lights on and somehow the the headlights have gotten out of sync! One light is up while the other is down. Every time I turn the lights off or on, the driver's light is up while the passenger light is down and vice versa. It seems that the driver's side light is getting power to lift up when I turn the headlight switch off.

    I've disconnected the battery, reversed motor relays and unplugged the drivers side lift motor, but cannot get them to both be down or up. Maybe the headlight stalk switch let go?

    Has anyone had this problem or offer any suggestions? Thanks.
     
  2. Spasso

    Spasso F1 World Champ

    Feb 16, 2003
    14,656
    The fabulous PNW
    Full Name:
    Han Solo
    #2 Spasso, Nov 11, 2011
    Last edited: Nov 11, 2011
  3. Darolls

    Darolls F1 Veteran
    BANNED

    Jul 2, 2003
    7,782
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    Sparky
    #3 Darolls, Nov 12, 2011
    Pull the plastic piece off of the stalk(be careful as there's a spring and small ball bearing in there).

    You will now be able to see the electrical connections and if loose, repair them. It is a common failure.
     
  4. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    #4 Paul_308, Nov 12, 2011
    Firstly, this particular problem isn't in the stalk switch, it simply powers the master lift relay. The master lift relay feeds power to the right and left sides, which are independant in themselves and must be analyzed separately. It's really than a matter of using logic to narrow down the problem to relay, contacts, or diode. These form a circuit to power the motor for that side.

    A bad diode will not power a motor to raise or to lower. Do both sides raise and lower at some point? If yes the diodes are OK.

    As you have reversed the relays and still have a problem you may have simply reversed problem sides. Concentrate on right and left separately, leave the master lift relay in place, remove right relays. Does that left headlight now act properly? If so, place THAT relay into the right socket and note it's action. Repeat this to learn if either relay works good on right or left side. If both relays act the same, the problem is in the contacts in the pods or wiring to the pods.
     
  5. umsneeze

    umsneeze Formula Junior

    Nov 16, 2004
    449
    Knoxville, TN
    #5 umsneeze, Nov 13, 2011
    Check the lifting mechanism. Iirc there is a cam shaped piece between the motor and the light. Mine had a loose bolt causing the lights to be out of phase. Mechanical not electronic.
     
  6. Paul_308

    Paul_308 Formula 3

    Mar 12, 2004
    2,345
    #6 Paul_308, Nov 13, 2011
    Last edited by a moderator: Sep 7, 2017
    Certainly a possibility if the link from motor/gearbox to headlight pod came loose and got shifted 180 on the shaft at #10 below.
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  7. fiatbrett

    fiatbrett Karting

    Aug 20, 2009
    98
    Tallahassee, Florida
    Full Name:
    Brett B
    #7 fiatbrett, Nov 14, 2011
    Thanks all, it turned out to be the lift rod rotating from a loosened bolt. I took it off dropped the light down and re-tightened and that fixed it! Thanks again for the help.
     

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