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Turn signal/brake light/tail light issues

A

Andy69

Well-Known Member
Senior Member
Trying to get the lights squared away in the Autowire harness in my 69.

Headlights tailights and marker lights seem to be fine.

brake lights are intermittent. Sometimes I have none, sometimes both, sometimes one or the other. I’ve traced it to the connector area at the turn signal switch under the dash. I can see the intermittent nature with the test light. I’ll have power one second and the light works next no power. This is true for the LH RH turn signals front and rear, and each brake light. Twisting the connector around to activate an open if there is one doesn’t seem to have an effect. I have the same issue with the white power wire. Sometimes no lights will work and there is no power at the white wire. Sometimes the white wire is hot and some lights work but others. I’m leaning toward the turn signal switch being bad?

Turn signals don’t flash. When I have power at the connector and activate the turn signal, the corresponding wire flashes the test light so I know it’s working. I seem to remember that turn signals are finicky about complete circuits so maybe the power issue or the turn signal switch is to blame.

Any ideas?
 
Have you confirmed constant power at the brake light switch, as in repeatable results each time the pedal is depressed?
 
Yes, but I ended up replacing the switch anyway since the threads were damaged
 
And that brake wire goes through the directional switch? Been a while and haven't looked, but I was under the impression the brake lights were independent of the directional switch.
 
I'm not sure. I've been trying to find a diagram of the actual switch itself. I'd like to know what's supposed to be happening inside the switch.

The white wire in from the brake switch is labeled "brake lamps" on at least one of the switch connector diagrams I've seen. Power should only be present at the white wire at the TS connector when the brake pedal is depressed (switch is released). That would necessarily be separate from the turn signals which work regardless of the brake switch position.

I'm going to pull the wheel next, see what's happening. It's the switch that was on the car when i got it. I repaired it years ago with a new cancel cam.
 
Last edited:
Andy69 said:
No.
Click to expand...
Good. I ran into a bad reproduction turn signal switch assembly, drove me nuts.. Ended up using one out of my storage shed with the adapter harness. That is one thing to check, make sure the connection is correct and the pins line up, sometimes an adapter harness is required.
 
Okay, I'm assuming you didn't have to mod the plug end to the directional switch where it plugs into the new harness, correct? If that's correct, I'm assuming you've tested the brake wire before and after that connector, and did the line test out fine on both sides?
 
Not sure if this will help but when I had No brake lights but everything else worked I replaced both flashers and that fixed my brake light problem, neither of my brake lights were working though
 
kmakar said:
Okay, I'm assuming you didn't have to mod the plug end to the directional switch where it plugs into the new harness, correct? If that's correct, I'm assuming you've tested the brake wire before and after that connector, and did the line test out fine on both sides?
Click to expand...

The TS switch plug is unmodified. The opposite connector is part of the Autowire harness. I can't remember if I needed to build that connector or just insert the ends into the plastic bit. I have double checked to make sure they are in the correct order. I'm pretty sure it's not the connector since I've had continuity every time I've tested for it.
 
Andy69 said:
The TS switch plug is unmodified. The opposite connector is part of the Autowire harness. I can't remember if I needed to build that connector or just insert the ends into the plastic bit. I have double checked to make sure they are in the correct order. I'm pretty sure it's not the connector since I've had continuity every time I've tested for it.
Click to expand...
1696512820733.png

Just for reference concerning the switch and harness.
 
Andy69 said:
The TS switch plug is unmodified. The opposite connector is part of the Autowire harness. I can't remember if I needed to build that connector or just insert the ends into the plastic bit. I have double checked to make sure they are in the correct order. I'm pretty sure it's not the connector since I've had continuity every time I've tested for it.
Click to expand...

Well, at this point it looks like fault in the switch. I'd venture to say it's worn. Easy test would be to try a secondary switch without installing it, just plug in the harness and ground it, so if I were in your shoes before you go further down the rabbit hole, buy another switch and test. If the new switch works, you have your answer, and if it doesn't, return the switch and dive into pulling it all apart.
 
kmakar said:
Well, at this point it looks like fault in the switch. I'd venture to say it's worn. Easy test would be to try a secondary switch without installing it, just plug in the harness and ground it, so if I were in your shoes before you go further down the rabbit hole, buy another switch and test. If the new switch works, you have your answer, and if it doesn't, return the switch and dive into pulling it all apart.
Click to expand...

I was going to pull it apart today but O'Reilly has new ones for $42 and I can pick one up today.
 
Replaced the switch. It really needed to be replaced. There were cracks in the plastic and all kinds of mayhem. Still didn’t fix the problem though. Could it just be a bad ground at the lights?
 
Andy69 said:
Replaced the switch. It really needed to be replaced. There were cracks in the plastic and all kinds of mayhem. Still didn’t fix the problem though. Could it just be a bad ground at the lights?
Click to expand...
Yes, sure could be, bare metal connections are required.
 
Andy69 said:
Replaced the switch. It really needed to be replaced. There were cracks in the plastic and all kinds of mayhem. Still didn’t fix the problem though. Could it just be a bad ground at the lights?
Click to expand...

Yes. I have had this problem multiple times. I've always had problems with the prongs making good contact. As of late, I have come to replace the socket in question, test to make sure it's working properly, then pop the socket back out of the light and coat both surfaces (prongs especially) with dielectric grease to protect them and it's worked out well without any further issues.
 
I’ll bet that’s it. I dont remember if I cleaned the surfaces off after painting.

Turn signals still not working. But at least now the dash turn signal lights come on when I press the brake pedal 😅
 
On the plus side, all the lights that are supposed to work do so when I pull the headlight switch. Also have the courtesy lights working.

Turn signals are a bit baffling. I know they are finicky and like to have all the proper lights in working order in order to flash, but they all seem to be.
 
Just get yourself some dielectric to coat the surfaces and you'll never have to deal with it again. Come to think of it, the problem for me has almost always been prevalent in the convertibles.

I think because the drains never really work properly and water always gets into the trunk area and the moisture eats away at the exposed metal first.
 
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