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Lucas Directional Switch (turn signal)

Posted: Fri Jun 23, 2023 3:05 pm
by robertscottcostello
Turn signal quit working so I peeked inside. I can make sense of the left which is still hooked up, but I wonder why the right has a common copper lead going to another post? No idea where the third wire would go.

Dumb question. It seems the key needs to be on to get power to the switch. Are the two small lamps on the front wings also turn signals, or are they only parking lamps?
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Re: Lucas Directional Switch (turn signal)

Posted: Fri Jun 23, 2023 6:00 pm
by Duncan M
Only the EXU cars had turn signals and a turn signal switch. TC7556 is not an EXU car, so you could have any number of possible arrangements to your turn signals. Always best when toubleshooting turn signals to check the bulbs on the bad side-- and whatever grounds and power supply they may have.

Re: Lucas Directional Switch (turn signal)

Posted: Fri Jun 23, 2023 6:01 pm
by Steve Simmons
I've had several of those switches, and every one of them had a different arrangement on the back. And every one of them confused the heck out of me. I don't know if they made them in different configurations for different functions or what.

Re: Lucas Directional Switch (turn signal)

Posted: Sat Jun 24, 2023 5:14 am
by robertscottcostello
I have a reasonable expectation that I have re-wired it correctly by tracing the wires back to the Lucas DB10 relay. Back to diagnosing the problem. None of the turn signals work. I have front, rear, left and right. The suddenness of the failure lends me to think it is component related and not ground. Going to look one more time to see if there is a fuse I have not discovered.

Re: Lucas Directional Switch (turn signal)

Posted: Sat Jun 24, 2023 5:55 am
by robertscottcostello
Fixed. Also, I found a 30 amp fuse on the voltage regulator which was too long, so I wrapped a piece of aluminum on it until I can get replacements.

Root cause was loose wiring in the Lucas SD84 turn signal switch.
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Re: Lucas Directional Switch (turn signal)

Posted: Sat Jun 24, 2023 7:07 am
by Steve Simmons
I wish they were all that easy. I had one of those relay boxes go crazy once. Took quite a while to readjust it.