What the hell did I do?

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Joined
Mar 1, 2011
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Location
Australia
My Car
1972 Sprint Sportsroof
Well I drove home tonight, lights and flashers working fine. Before going inside I thought I might check if the rear lights were functioning properly.

Everything was working properly, but I noticed on the far left that a portion of my "plasma" LED tail light globe was a little flaky.

So I ran inside, grabbed another plasma globe. I still had the lights on and the left flasher working when I swapped out the globe, which was clearly a mistake. Because when I inserted the globe I put it in backwards first up, and while it did briefly light up, it was clear I had inserted it backwards as the globe wouldn't spin into position because of the staggered pins being in the wrong orientation.

So I spun it around and inserted it correctly, all good, the taillight lit up and the rear flasher functioned normally.

However, when I disengaged the flasher lever, the rear flasher stopped but the front flasher was running all by itself. Also the headlights were out.

I traced the headlight problem to a severely burnt out inline fuse. When I had put the rear globe in backwards I surmise it shorted out somehow....

But that front left indicator still now blinks all by itself when the ignition is turned on and the flasher lever is in the off position. Moving the flasher lever to the left gets the rear light flashing normally in unison with the front. Moving the lever to the right gets the right flasher working properly, but the front left keeps blinking at the same time. Turning on the hazard flashers works correctly, and the hazard flasher unit correctly overides the turn flasher unit above the glovebox, so I don't think this problem has anything to do with the hazard circuit.

So in summary, is there any electrical guru's out there that would know why a front flasher light would operate by itself with the indicator lever in the off position??

 
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I'm guessing that it's the turn signal switch. The same short that took out the fuse may have damaged the turn signal switch or emergency flasher switch, maybe fusing contacts or wires together. You can pull out the flashers, one at a time, to see if the problem is in the turn signal or emergency flasher circuitry.

 
I'm guessing that it's the turn signal switch. The same short that took out the fuse may have damaged the turn signal switch or emergency flasher switch, maybe fusing contacts or wires together. You can pull out the flashers, one at a time, to see if the problem is in the turn signal or emergency flasher circuitry.
I'm with Don here... - the large transient current on putting a device in backwards may have touch welded the small brass spring and copper tipped contacts together in your turn signal switch or something is holding the flasher relay on. Those contacts are made for only a few amps ... not a massive inrush current.

Flasher relay has a small circuit embedded that charges and discharges the relay coil to give you a flash. The turn signal contacts could be spot welded to closed position holding that relay to stay energized.

The best way to check this is with a multimeter --you may need a puller if you need to get your steering wheel off - not sure where the relay is located

However LED based products ought to have anti- reverse polarity protection in them if designed with some thought. A diode that only allows the current to go one way.

 
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Thanks guys, you got it in one, I have damaged the turn signal switch.

I remembered that quite a few years ago I had bought a brand new turn signal switch off ebay for "just in case" insurance, though it took some determined ferreting around in my basement to find it.

Unplugged the turn signal from under the dash and plugged in the new one and everything was back to normal. Will install the new switch later in the week now that I know it will fix the problem.

Mental note for next time: leave the indicator and lights off next time I install a globe....  :chin:

 
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