Yet Another Turn Signal Woes Thread - Front signals don't/barely work with headlights on

[Slonie]

Hi folks,

 

So I've got an issue that isn't quite the same as anything I've found via search (here and elsewhere) and wanted to bounce ideas.

 

My turns signals work fine, when the headlights are off. I've previous had some variant of the "they stopped working until I toggled the hazard switch several times" failure, but hasn't happened too much recently.

 

When I turn the parking lights or headlights on (i.e. first and second position on the headlight switch) the front turn signals/indicators under the headlights stop working. They actually might be flashing but extremely weakly. Like, need-to-remove-the-lens-and-stare-at-the-filament weakly.

 

I've taken the hazard switch apart and wiped off the contacts inside, and sprayed Deoxit inside (although I have to admit it "looked pretty clean" inside, my car is only 25 years old after all). This didn't seem to change anything. I have not tried buying a new hazard switch.

 

Some other notes and observations from memory, as I'm not in the garage right now.

 

1. I've recently installed both Just Add Lightness LED Taillights installed, and CaterLED repeaters in back, although I'm not sure if this behavior is new with those recent additions. I don't think it is (but I just noticed it when going over the operation post-install).

 

2. I'm using a new (generic) LED flasher relay, one of two that I had on hand (both of the above came with one and while they looked identical, they had slightly different behavior, I picked the one that flashed more slowly) 

 

3. I've previously had woes related to the wing indicators / turn signal repeaters on the fenders that I've seemingly resolved by removing the ground wire and cleaning up the ring terminal and washers (and sanding a bit around the hole in the wingstay). In some cases they wouldn't work at all or were very dim on one side. I've tried cleaning them up on both sides and they are working fine right now.

 

4. I've noticed different rates of flashing between having the headlights on and off with the hazard switch. Nothing that bothers me that much but...

 

5. I've always thought my car's flashers seemed fast but I don't really have much to compare against. I think they slowed down with the LED flasher relay I installed recently.

 

6. The big connectors for (I assume) the front lights are missing the retaining clips on my car and can be pulled apart easily, but manually pushing them together more tightly didn't change any behavior.

 

So, any ideas? Of course my suspicion is a bad ground somewhere, but I'm not sure how the front indicators ground (unlike the fender ones). Also, they seem to work okay as long as the headlights are off. Everything else seems to be working fine in the signal and hazard department.

 

Thanks for any ideas or tips for where to trace!

[Scott_]

My guess is a bad ground.  Run a jumper from the negative pole of your battery to the negative lead of your front turn signals and see what happens.

 

Scott

[Carz01]

@Slonie I had something similar occur when I changed to LED’s. I’d suggest before chasing wires to change the bulbs back to make sure the wiring is ok and everything works correctly. You might change the bulbs one at a time to test. In my case changing back to non-LED proved everything worked, correctly flashing, and it turned out to be a faulty relay.

[JohnCh]

12 hours ago, Slonie said:

When I turn the parking lights or headlights on (i.e. first and second position on the headlight switch) the front turn signals/indicators under the headlights stop working.

 

I agree with @Scott_. It sounds like a ground issue. I'd start by measuring voltage drop for each turn signal bulb assembly and see if one is an outlier.

 

[Joe Petty]

The bad ground suspicion is a good place to start.

Clean all the grounds (front and back) and use those star/tooth washers and electrolytic grease.

 

Interesting that the headlights cancel the turn signals!

Assuming that it is a bad ground that is causing the problem, it may be that a headlight/marker light cannot find a good path to ground and the current is attempting to "back up" through the turn signal circuit.

 

Disconnect the headlights (pull the plugs) to determine if it is the headlamps or the marker lights and that may help in isolating the cause of your problems.

 

Formula 1 this weekend, so take some breaks and mull over what might be going on!

 

Good Luck - Joe