Battery Drain... Solenoid?

Discussion in 'Classic Mustang Specific Tech' started by Joop, Sep 18, 2008.


  1. Joop

    Joop New Member

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    I fully charged my optima in my 67 w/ 289 a week ago. In the mean time I was working on some other issues with the car and have been starting it every once in a while. Yesterday I could hear the battery getting weaker while turning over.

    I then disconnected the battery and trickle charged it overnight.

    This morning it is fully charged, now to find the short. I put the positive cable back on the battery and took the negative off. I then hooked up a test light to the negative cable to the negative terminal... and we got a light. So that means a short somewhere.

    I knew exactly where it was, didn't even go to the fuses, and pulled the small brown wire off of the solenoid. The test light went out. So I assume the short is in the ignition... but I wonder if it is the solenoid?

    My question, how can I test to see if the solenoid is bad? I replaced it about 2-3 summers ago, but it may have gotten fried with all the other electrical problems that have been happening (engine run-on).

    Can anyone confirm my tests and tell me how to test this thing? Thanks!!!!

    Joop
  2. Joop

    Joop New Member

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    I've been doing some searching and found this on another site...

    when I jump the terminals, it does turn over so on to the next test.

    I checked the voltage at the S terminal with the key on, and i don't get a reading at all, but I DO get a reading at the I terminal when the key is on. So my results are backwards according to this test.

    Also, the readings I get are not 12 volt, they are closer to 18 volts...
    So is the voltage regulator fried?

    I think I'm going to go get a VR and a Solenoid and see what happens...
    ... but I could still use some input.
  3. Joop

    Joop New Member

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    Bought a new solenoid and voltage regulator....

    Installed the VR, same short.

    Installed the solenoid... no short! and it fixed my engine run on problem too!

    thanks for the help... well, no replies but my own but....

    I won't hold it against ya.
  4. BarnStang

    BarnStang Founding Member

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    Too funney! :) Sometimes we just sit back and listen...
    I think this is an interesting problem cause I have yet to see a failed solinoid, well maybe one-intermittant contact when trying to start. You will only see 12v on the S term with the wire connected. The 12v comes from the wire to the solinoid to key the relay and pull the contacts down. THe S term is one side of the coil, the other is ground.
    I was going to say that you have a test light indication because of the coil, but if the switch is off then you should not see a drain. The brown wire sends 12v out from the solinoid in the Start pos of the switch down the brown wire to end up at the coil. You will then see 12v coming back down the brown wire via the pink resister wire. You will see an idication there when the car is running, but it doesent do anything-only function is full 12v to the coil in Start. So with the brown wire off, you should see 12v at the I term when the relay (solinoid) keys or engages-Start position of the switch, or short battery term to the S term.
    If I were to guess, I would guess the I term somehow had carbon trace or broke inside and made a connection wit the relay contacts inside, or more likly, the spring got weak and didn't retract the contacts fully. THat would cause you to have a hot ignition all the time. It would be the same as running a wire from the battery to the coil. Great troubleshooting though! Well done!

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