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308 Window electrical issue

Discussion in 'Technical Q&A' started by benjammin308, Jul 12, 2005.

  1. benjammin308

    benjammin308 Rookie

    Apr 8, 2005
    40
    Racine, WI
    I know this is a much discussed topic but I haven't found my particular problem described before. The passenger window on my '85 Euro spec QV used to work fine, then stopped going up (still goes down fine). I took the door apart to do the standard 308 window service desribed in detail in previous threads, and found that the motor would not go in the up direction, even with no load. A meter on the motor wires showed +12V in one switch position and -12V in the other switch position, so I ordered a new motor. Same problem with new motor. Just for kicks I swapped out the window relay with no improvement. What's going on?
     
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  3. cgperry

    cgperry Formula Junior
    Rossa Subscribed

    Nov 2, 2003
    504
    Chas SC
    Full Name:
    Charles Perry
    My guess is that you have a short to ground on one lead on the motor side of the connection. I don't know how the 308 wiring is done to the motors, but this is all I can think of that would cause the problem with two different motors.

    My logic is thus: You measured the voltage to the window at some connector in the door. Voltages seem to be working correctly. Let's call that the CAR side of the connector. On the MOTOR side of that connector, there is a short to ground on one lead.

    To figure out which wire, see what the polarity is when the window switch is in the down position. Whichever wire is the negative in that situation is the one that has the short on the motor side. Thus, when you press the down button, you get 12V on the positive wire and you're already shorted to ground on the negative wire, so the window goes down.

    When you put the switch in the up position, the polarity reverses. Now the wire that was the positive is the ground, and the wire that SHOULD be the positive is shorted on the motor side, so you have ground on both sides of the motor and the window can't go up.

    Now, in theory if you had a full short, it should pop the window motor fuse when you press the UP button. Since it doesn't, it may not be a dead short - it may be a few ohms, in which case you're drawing a lot of current but not quite enough to burn the fuse.

    Again, I don't know the 308 motor directly, but you can test this by removing the motor from all the car wiring and just hooking it directly to a 12V battery. In one polarity the motor should spin one way, and with the polarity reversed it should spin the other way. If it does, your problem is definitely between the motor side of that door connector and wherever the wires hit the motor itself.
     
  4. wolftalk

    wolftalk Formula Junior

    Jan 27, 2004
    367
    san franciso area
    Full Name:
    phil
    The two wires from the motor go directly to the window switch. The switch does the job of connecting/swapping +12V and ground to the two wires.
    The antenna works the same way.

    The problem is almost certainly in the switch.

    You can take the switches apart and clean the contacts inside. I don't remember if that switch has springs and balls in it, so take it apart over a towel so pieces that fall out don't wander off. You might even get away with just hosing out the inside of the switch with a electrical cleaner without taking it fully apart.

    You may be able to pop the switches out of the console without removing the ashtray/screws and lifting the front of the console. However, if they don't want to come out easily, lift the console. You don't want to chew up the fiberglass around the switch hole, otherwise the switch will be loose.

    I think the consensus was that the switch itself is the main cause of slow window operation. While hardend grease on the worm screw doesn't help, the switch just can't handle the current the motor really wants.
     
  5. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
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    May 4, 2001
    31,634
    Birmingham, AL
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    Tommy
    If it is the switch, It is EXACTLY the same as in an 82 Alfa Romeo Spider. Call International Auto Parts and save $20.
     
  6. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Rossa Subscribed Owner

    May 4, 2001
    31,634
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    Tommy
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  8. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
    NWA
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    Paul

    Anyone make a better switch? One that doesnt look out of place?
     
  9. wolftalk

    wolftalk Formula Junior

    Jan 27, 2004
    367
    san franciso area
    Full Name:
    phil
    If I remember right, the wire gauge to the switch doesn't help either, so just replacing the switch may not be enough.

    I know I verified that connecting the window motor directly to a battery at the motor connectors caused the window to whiz up/down like you'd expect.

    I don't remember if I then pulled the connectors from the switch and jumpered the battery directly to the connector plugs. Doing that would eliminate the wiring and leave the switch.

    Final test would be jumper the battery through the switch to see if the switch really is the problem. If not, then it's the 12V supply to the switch.

    The most effective fix was to put relays in the circuit so the console switch operated the relays, and the relays controlled the motor using a good 12V supply. I think someone posted a detailed drawing using 4 relays - 2 for each window.
     
  10. benjammin308

    benjammin308 Rookie

    Apr 8, 2005
    40
    Racine, WI
    Thank you for all the input. I've ordered a switch and should know if it helps by the weekend. The larger wire and relay fix sounds like a great project for this winter, but right now I just want to get back on the road. Our Wisconsin summer is short!
     
  11. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
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    May 4, 2001
    31,634
    Birmingham, AL
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    Tommy
    Forget relays, meters, battery jumping, etc. The simple way to check the switch is just to swap switches. If the driver's side works fine just plug it in on the passenger side and see what happens.
     
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  13. Dr Tommy Cosgrove

    Dr Tommy Cosgrove Three Time F1 World Champ
    Rossa Subscribed Owner

    May 4, 2001
    31,634
    Birmingham, AL
    Full Name:
    Tommy
    See my post above. Exact same switch.
     

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