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Thread: Inertia switch failure, tripping thermal relay of door lock electrical?

  1. #1
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    Inertia switch failure, tripping thermal relay of door lock electrical?

    My car has worked well for a long time. This weekend after (externally) locking door and unlocking I noticed my thermal relay in door circuit began "tripping" constantly on way home.

    Could the inertia switch cause this behavior?

    Any help appreciated, I don't know where to test first to find this fault and correct.

  2. #2
    DMC Midwest - 815.459.6439 DMCMW Dave's Avatar
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    Yes that is how it is supposed to work. It unlocks the doors in an accident so you can get out of the car.
    Dave S
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    dswingle@DeLorean.com

  3. #3
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    Quote Originally Posted by DMCMW Dave View Post
    Yes that is how it is supposed to work. It unlocks the doors in an accident so you can get out of the car.
    Thanks Dave, The inertia switch is causing the relay "tripping" then? I don't have an extra to test this new behavior from my doors, so just replace the switch?

  4. #4
    DMC Midwest - 815.459.6439 DMCMW Dave's Avatar
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    Quote Originally Posted by ritztoys View Post
    Thanks Dave, The inertia switch is causing the relay "tripping" then? I don't have an extra to test this new behavior from my doors, so just replace the switch?
    Unplug the switch and the locks should act normally. But the fuel pump will be disabled (car won't run) unless someone has bypassed it somewhere else.

    You can temporarily bypass the inertia switch to ground the fuel pump to drive the car.
    Dave S
    DMC Midwest - retired but helping
    dswingle@DeLorean.com

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    Quote Originally Posted by DMCMW Dave View Post
    Unplug the switch and the locks should act normally. But the fuel pump will be disabled (car won't run) unless someone has bypassed it somewhere else.

    You can temporarily bypass the inertia switch to ground the fuel pump to drive the car.
    Thanks again Dave, I now know what to do. The door lock "brains" are kinda of 'salty' in $$, inertia switch is easier on the wallet!

  6. #6
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    Well........ after removing inertia switch from circuit and testing as suggested, the problem remains?

    Could the door lock "brains" internally be causing my lock problem? The thermal relay "trips" as soon as I connect the battery? (with inertia switch removed)

    Should I open the door trim and check the electrical inside of the door? Could mechanical parts of door lock cause this problem?
    Last edited by ritztoys; 09-11-2017 at 11:43 AM. Reason: additional questions

  7. #7
    DMC Midwest - 815.459.6439 DMCMW Dave's Avatar
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    Inertia switch failure, tripping thermal relay of door lock electrical?

    You could just disconnect the module. Locks will still work manually. It's likely that you have a bad solenoid or two in the doors, that can cause similar issues.

    The inertia switch may not be the issue, more likely are solenoid or the lock module.

    Sent from my iPhone using Tapatalk
    Dave S
    DMC Midwest - retired but helping
    dswingle@DeLorean.com

  8. #8
    Senior Member Bitsyncmaster's Avatar
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    There was a problem with the OEM door lock controllers with sticking relays but that would normally just over heat the solenoids and then you got locked in the car. When I first got my car, the door locks would intermittently click on and off when driving. That just turned out to be a bad connector pin on my door lock unit. I designed my own door lock controller anyway to prevent the relay sticking problem of the OEM unit.
    Dave M vin 03572
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    Thanks for your experience in trouble-shooting this issue. As far as I can tell this is an original door lock controller, when I disconnected the multi-pin connector from the wiring harness and then re-connect the multi-pin, I see a spark when doing this(maybe a bad solenoid). Then the thermal relay begins to open & close with that loud 'click' continuously.

    So........my trouble-shooting experience tells me (and after reading your post), I have a 'frozen' relay or two in the door lock controller, or maybe a bad solenoid?

  10. #10
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by ritztoys View Post
    Thanks for your experience in trouble-shooting this issue. As far as I can tell this is an original door lock controller, when I disconnected the multi-pin connector from the wiring harness and then re-connect the multi-pin, I see a spark when doing this(maybe a bad solenoid). Then the thermal relay begins to open & close with that loud 'click' continuously.

    So........my trouble-shooting experience tells me (and after reading your post), I have a 'frozen' relay or two in the door lock controller, or maybe a bad solenoid?
    Yes, sounds like a relay is stuck on.
    Dave M vin 03572
    http://dm-eng.weebly.com/

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