Thread: electrical puzzle

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  1. #1 electrical puzzle 
    Little Brit
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    Sep 2017 06:13

    This is a head scratcher. Will take more than casual thought.
    Two days ago 1981 TR8 would not shut down it's starter after ignition. I shut engine down with key, starter continued churning away. Pulling the negative battery cable killed it. Thinking starter solenoid was stuck,I pulled starter but bench testing it proved to be fine. It is still out of the car. White - orange solenoid wire was still hot without key on though. I could hear the starter relay in the footwell 'click' each time I touched the negative back to the battery. Working back from that relay I went to the ignition - switch. As it should be the only source of power to the starter relay I thought perhaps something had come adrift internally causing the white - orange wire to be hot all the time,,, but after disconnecting the switch harness, that is, taking it right out of the system, the relay still 'clicked' when the battery negative was touched, and of course the solenoid wire at the starter was still hot. So next stop was that little relay itself. I pulled it and of course that killed the power to the solenoid wire. Plugged it back in again and the weird part is all is now good. Even though the relay was clicking nicely I of course thought I'd reached the correct conclusion. Being curious I wanted to see what it looked like inside and expected some burnt and stuck little parts. Well the damn thing is perfect and works on the bench just as advertised every time. Now it also is working just fine with the ignition switch as well. I'm naturally reluctant to just put the starter back in and call it good because something somewhere was activating that relay without any input from the ignition, and of course I'm worried it'll happen again, but what? What could possibly energize the starter relay except the ignition switch? And then stop after simply removing it, then plugging it back in?
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  2. #2  
    I would repalce the relay as it does have power all the time Via the brown wire, the internal points could be sticking. You swap it with another blue relay or Red. Cannot use a black
    The Wedge Shop
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    www.thewedgeshop.com
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  3. #3  
    Little Brit
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    Quote Originally Posted by The Wedge Shop View Post
    I would repalce the relay as it does have power all the time Via the brown wire, the internal points could be sticking. You swap it with another blue relay or Red. Cannot use a black
    It does have power via the brown all the time but that has nothing to do with relay energizing. That duty is via the white/red wire. The relay was carefully taken apart with a Dremel and the points were bright and shiny with absolutely no sign of any sticking ever. The relay happily clicking away 100% on the bench.
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  4. #4  
    Young Brit
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    Feb 2012
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    What is the difference between the different color relays?
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  5. #5  
    Little Brit
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    Quote Originally Posted by TR8 View Post
    What is the difference between the different color relays?
    I've ordered one from Del City, P/N 73996. It is configured exactly like the Lucas 33365D inside but it is square and black while the Lucas unit is round and blue. It is also rated at 30A rather than the Lucas's 20A (this is good) and it cost a total of $15.69 (this is also good) rather than the Wedge Shops price of $106.00 + postage for the obsolete Lucas unit. YIKES!

    https://www.delcity.net/
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