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Headlight Electrical Issues

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Old Aug 20, 2018 | 03:34 PM
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Default Headlight Electrical Issues

I previously started a thread here that outlined my issues, but I slowly realized it had gotten too far away from what was really wrong with the car (although still very helpful).

My issue is that my parking lights/DRL are being strange and causing some electrical issues with my C5Z @ 114K miles;

-Turning the parking lights on does nothing (headlights don't flip up, no parking lights) except illuminate both turn signals as if I had my hazard button held down and kill the LED on my dash and the AC unit.
-If I leave all of the lights off, once I disengage my parking brake, the LED on both the DIC and my AC unit start to flicker repeatedly. This behavior continues until the car is turned off or until I flip the parking or headlights on -- which causes the DIC and AC unit to go completely dark/off along with both turn signals being solid as described above. While the parking brake is still engaged, nothing is that out of whack. I was hearing some loud buzzing coming from the passenger footwell fuse box, and replaced fuse relay #38 and #40 (DRL/L and DRL/R) since I could feel them vibrating, as well as replacing fuse #2 in the engine fuse box just in case (Approach Lights) -- this didn't change anything.
-Putting on my turn signals causes both turn signal indicators on the dash to blink (faster than the normal turn signal), and the turn signals/DRL and brake lights do in fact work.
-My hazard button does not remain on when pressed. When released it goes back to off rather than remaining on, and does not click down. I've read lots of similar threads and many suggest replacing the hazard switch. Thoughts?
-All grounds appear to be clean and have been cleaned within the past 6 months.
-I do have a custom headlight kit installed (projector HID), but they were installed over a year ago and have had no electrical issues until this point.
-No codes being thrown.
-Just replaced the battery.
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Old Aug 20, 2018 | 04:14 PM
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Did some mice get in your car and chew up your wires? That is literally the only thing I can think of that can cause what you're seeing. Shorts due to exposed wires somewhere.
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Old Aug 20, 2018 | 04:17 PM
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I don’t think it could be mice since the car is garaged and I’ve never seen one before.

I did install an SLP blackwing air intake within the past month or so, but the MAF cable looks healthy and was handled with care.
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Old Aug 20, 2018 | 06:21 PM
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Check the front turn signal sockets. Water can get into those and corrode the contacts. There is also the possibility your MFS went bad. Check your wiring under the dash to see if there is any loose/frayed wires.
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Old Aug 20, 2018 | 06:28 PM
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Originally Posted by Tsumi
Check the front turn signal sockets. Water can get into those and corrode the contacts. There is also the possibility your MFS went bad. Check your wiring under the dash to see if there is any loose/frayed wires.
Thanks for the quick responses, it's much appreciated.

I don't believe it's the bulb housings since I replaced the OEM headlights with this kit within the past year and the car hasn't touched water other than a hand wash (I guess it's still possible though);
https://www.corvettemods.com/C5-Corv...hoCppUQAvD_BwE

I'll definitely take a look at the cabling diagrams and see if there is any wear/damage but I've followed the majority of the cabling I can see and nothing looks out of the ordinary, although I'm a very novice garage mechanic. Do bad cables usually have copper exposed? The worst I've seen is some cable exposed out of the wire loom (cable protective plastic still fully in tact).

Does anyone have any thoughts about the hazard switch? It just seems far too coincidental that the warning button doesn't stay clicked in, and I'm now seeing electrical issues that somewhat relate to the warning light indicators.

Last edited by CapslockAnt; Aug 20, 2018 at 06:52 PM.
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Old Aug 23, 2018 | 01:03 AM
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Update: fuse relay 38 and 40 are the relays that were screaming whenever the electrical would get goofy on the dashboard and AC unit. I pulled the fuse relays and now almost everything is back to normal with the exception of my front turn signals. With the fuse relays pulled, flipping the turn signals on flashes the turn light on the dash faster than normal and the front turn signals do not come on.

Bad turn signal bulb?

Last edited by CapslockAnt; Aug 23, 2018 at 01:04 AM.
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Old Aug 23, 2018 | 01:16 AM
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Possible bad ground? That's what I would check. Make sure your BCM plug connections are tight as well. And I would double check the front turn signal bulb socket.


The turn signal goes through the relay to get to the front turn signal lights. It makes sense that removing the relays caused your front turn signals to not work.
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Old Aug 23, 2018 | 01:38 AM
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Originally Posted by Tsumi
Possible bad ground? That's what I would check. Make sure your BCM plug connections are tight as well. And I would double check the front turn signal bulb socket.


The turn signal goes through the relay to get to the front turn signal lights. It makes sense that removing the relays caused your front turn signals to not work.
I see now, and agree that this would explain the front turn signals. That diagram is very helpful, thank you.

I have this spidey-sense that it's related to the Hazard Switch, especially after looking at this diagram. The hazard button does not press down and stay compressed when I push it in. The lights on the dashboard that I was seeing when I turned the front lights and parking lights on (which both worked) were both turn signals on, at once -- just like as if the hazard lights were on or were somehow getting signal input from the switch.

I'll get a grounding diagram and make sure to check them all.
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Old Aug 23, 2018 | 02:33 AM
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Unplug your hazard switch and see what happens. You would lose your brake lights and turn signals though when you unplug it.
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Old Aug 23, 2018 | 05:52 PM
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Originally Posted by Tsumi
Unplug your hazard switch and see what happens. You would lose your brake lights and turn signals though when you unplug it.
That is a great idea, not sure why I didn't think of that before. I'll get to it this weekend and update with my findings.

Thanks!
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Old Sep 3, 2018 | 09:04 PM
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Update: I think I need to re-address my issues. I just cleared all codes, and drove the car a bit. It throws one single historical code B0367 for HVAC. As soon as I disengage the parking brake, the dash, AC unit and DRL all begin to blink on and off, and fuse relays 38 and 40 in the passenger footwell begin to open and close repeatedly until I turn the parking lights or headlights on, and then they go back to normal with the exception of both turn signals being solid on the dash and flashing with both turn signals.

I still have not tried disconnecting the hazard switch, but that will be my next step.

Grounding?
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