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Thread: TR3 electrical problem ignition or generator???

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    Question TR3 electrical problem ignition or generator???

    I'm in the final stages of a complete restoration of a 1959 TR3 . I've installed a new wire harness, new control box regulator and new generator. Engine starts and runs well. No generator light come on when starting, but the engine will not turn off when the ignition is turned off. The yellow wire to the generator light on the dash gets hot? Engine will stop when this yellow wire is disconnected. I've had the generator tor the shop and checked out ok. New control box adjusted from Moss installed no change. Traced the wiring out several times can't fine anything. Any suggestions would be helpful.

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    Great Pumpkin - R.I.P TR3driver's Avatar
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    Re: TR3 electrical problem ignition or generator???

    So the light doesn't come on, even when you first turn the key on? Does the ammeter go full negative at that point?

    My guess, the bulb holder for the warning light on the dash is shorted out or not wired properly. One side should be connected to the ignition switch, the other to the generator output. So when you turn the key off, power is flowing from the generator output (which also gets connected to the battery) through the short and into the ignition.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: TR3 electrical problem ignition or generator???

    Quote Originally Posted by TR3driver View Post
    So the light doesn't come on, even when you first turn the key on? Does the ammeter go full negative at that point?

    My guess, the bulb holder for the warning light on the dash is shorted out or not wired properly. One side should be connected to the ignition switch, the other to the generator output. So when you turn the key off, power is flowing from the generator output (which also gets connected to the battery) through the short and into the ignition.
    No light at all. The ammeter goes to full positive .

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    Re: TR3 electrical problem ignition or generator???

    I don't know what it is, but you have a miswiring problem. Get a decent diagram and go over the wiring again, starting behind the dash panel. The swing to full positive with the key on (assume the engine not running) also indicates that your polarity is backward.
    Bob

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    Re: TR3 electrical problem ignition or generator???

    Quote Originally Posted by 58Triumph tr3 View Post
    No light at all. The ammeter goes to full positive .
    Sure sounds like a short (or miswiring) at the dash lamp. Your ammeter wiring also doesn't match the battery polarity. If you have converted to negative ground, the leads at the ammeter need to be swapped to get it to read the right way.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: TR3 electrical problem ignition or generator???

    thanks. I have a good diagram and will start from scratch going over the wiring behind the dash . I'll have to wait until this sub zero weather changes here in western NY.

    Peter

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    Re: TR3 electrical problem ignition or generator???

    Quote Originally Posted by 58Triumph tr3 View Post
    thanks. I have a good diagram...
    Be aware that there were some changes along the way and be sure the diagram you have matches your car & harness. In addition to obvious changes (like the brake light and turn signals) there are others that are less noticeable and perhaps counter-intuitive (like the windscreen wiper switch & motor).

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    Re: TR3 electrical problem ignition or generator???

    Finally got out to the garage in the cold and checked the wiring to the generator light on the dash. Sure enough the two wires were shorted to each other . The light know comes on with the ignition turned on. Wasn't able to start the car, battery too low and still too cold.

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    Great Pumpkin - R.I.P TR3driver's Avatar
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    Re: TR3 electrical problem ignition or generator???

    Quote Originally Posted by Geo Hahn View Post
    Be aware that there were some changes along the way and be sure the diagram you have matches your car & harness.
    Quite true, but the charging circuit was always the same, even to the TR4A.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: TR3 electrical problem ignition or generator???

    Let us know how the engine starts and runs. It's below zero here in Connecticut; my TR has been in hibernation for two weeks.

    Assume you know about the TR wiring diagrams here:

    https://www.advanceautowire.com/schematics.htm

    Tom
    Mac & Phyllis Take a Trip: http://nutmegflyer.com/trip-details-daily-updates/
    History: 1976 MGB, 1959 Triumph TR3A, 1960 Mercedes-Benz 190b, 1958 Rambler American, 1953 MG TD.
    Next? who the heck knows!

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    Re: TR3 electrical problem ignition or generator???

    Temperature much warmer just about 32 so took the chance to start the TR3. All seems to be working fine. Generator light comes on with ignition, then off with engine running, amp meter looks good also. Thanks for the help, it always amazes me how such a little thing can cause such headaches.


    Peter

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    Great Pumpkin - R.I.P TR3driver's Avatar
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    Re: TR3 electrical problem ignition or generator???

    Shorts are pretty much always Bad Things. At least it didn't let the smoke out.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: TR3 electrical problem ignition or generator???

    Quote Originally Posted by TR3driver View Post
    Shorts are pretty much always Bad Things. At least it didn't let the smoke out.
    These days replacement smoke is available, so it's not a big problem.

    Art
    '58 TR3A TS236xxL
    '92 Mazda Miata -- Supercharged
    '07 Mazda RX-8
    '11 Mazda CX-7

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