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Hello! I was wondering how I would be able to test the turn signal switch in my 78’ Nova. I recently re-wired the entire car, but I’m lacking power to my front right turn signal. The rear right still works fine, and I’ve tried tapping into the rear turn signal circuit, but that leads to the front TS lighting up when I hit the brakes. Any idea how I could troubleshoot the TS wire not getting power?
I’ve already looked into ground at the headlight (ran to battery ground), power to flasher(ticks, And rear turn signal works), and tested power wire with a test light at multiple points through the engine bay. Any ideas would be appreciated.
 

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The turn signal switch has a connector clipped to the outer jacket of the steering column just beyond where it passes under the dash. It's a long flat connector, often called a "harmonica connector" due to it's shape. There should be 10 wires in that connector.

The purple wire supplies power to the switch (via the "B/U DIR SIG" fuse and signal flasher). When you flip the switch to the right, one of the connections it makes is between that purple feed wire and the dark blue wire that leads to the right front signal light. A branch of that dark blue wire also goes to the RH turn indicator in the dash.

So using your test light, check for power on the dark blue wire at the turn signal switch connector (check it on both sides to rule out a bad terminal in the connector).

And as a double check of all the other wiring, you can connect up a temporary jumper wire between the purple and dark blue wires at the turn signal switch connector. That should bypass that particular set of contacts in the switch and activate the right front turn signal if everything else in the circuit is okay.
 

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Keep in mind that there are two switch setups happening in the turn signal switch.

One part works with the front lights and the other part works with the rear lights.

The rear lights and switch to me has the most going on because when the turn switch is in the middle position, and the brakes are applied, voltage goes out to both brake light bulbs but when the left or right turn signal is activated then a connection gets switched over to a flasher for that side but still keeps a connection present from a signal from the brake witch.

The front signals on the one half of the turn signal switch assembly does not have a brake light input and only gets power from the turn signal flasher and then gets sent out to either the front left or front right signal light (as well as the indash indicator lights also wire to these lights).

I have a feeling that if you do not have a flashing output on the column connector for the right front as well as not having an indash indicator light coming on that the switch has an issue. If you have an indash indicator lighting up but not a light in the front end, then maybe it's a connection on the bulkhead connector or at the lights socket.



Maybe look at these drawings I did years ago on the operation of a turn signal switch:


Hopefully you are telling us enough to get things figured out and not adding later like you are running LED lights, some aftermarket flasher, or ???????. Some screwy things can happen when one wanders from the factory setup and have wrong things installed like LED's on the front marker light sockets.

The more we know the better the response. Just saying.

Jim
 

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Discussion Starter #4
thank you much for the input! Yeah I’m aware LEDs can cause problems, and I do have halo flashers up front, but I eliminated that issue by wiring in the old flashers still mounded to the grill and had the same issue. I’ll test the harmonica connectors for sure, and I do appreciate the schematic that you drew up. It has a few things that the manufacturer diagram was lacking in continuity. I’m afraid that if the switch is bad I might be forced to replace the steering column, but with the flashers working right before the re-wiring something has me doubting that is the issue. I’ll be sure to let you know that I find out. Thanks again!
 

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Unfortunately I’m still in the weeds with this issue, I ran my tests and I’m getting a signal from the harmonica clip, and I’m pretty sure the switch is working fine because the rear right tail light is functioning as it should. Like I said I spliced into the right rear to test the wiring to the turn signal, and that works, so now I’m just kind of stumped as to where things could be going wrong in between the harmonica clip and the fuse box. There is something strange going on with the front flasher when it is hooked up to the rear turn signal wire, and that is that it doesn’t flash, it’s just a steady “on”. At this point I am considering just bypassing the fuse box all together, but I can’t shake the feeling that there is something simple that I’m missing here...
 

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UPDATE: I got frustrated and took the “kick it a couple of times” approach with the issue and just scratched away at the harmonica clip connections with my test light. The problem is partially fixed, and the front signal now has power (hooray!). The issue of it not blinking still stands though. Any suggestions would help immensely!!
 
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