Puzzling issue (related to brake lights and turn signals) - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

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post #1 of 8 (permalink) Old May 23rd, 17, 07:31 AM Thread Starter
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Steve
 
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Location: Rochester Hills, MI
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Puzzling issue (related to brake lights and turn signals)

OK, guys, get your thinking caps on. I've got a puzzler of an electrical issue for you that, now that I think about it, may have been an issue for the entire time I've owned this car. I only noticed it last night as I was following my wife as she drove the '68 Camaro RS.

Here are the test cases.

With no lights on (headlights and parking lights off):
Turn on right turn signal. Outcome: Front and rear turn signals work fine.
Turn on left turn signal. Outcome: Front and rear turn signals work fine.
With no turn signals on, hit brake pedal. Outcome: All brake lights work fine.
With left turn signal on, hit brake pedal. Outcome. Front and rear turn signals work fine and so do right-hand brake lights.
With right turn signal on, hit brake pedal. Outcome. Front and rear turn signals work fine but NO LEFT-HAND BRAKE LIGHTS AT ALL.
Doing all those same tests with the headlights and parking lights on yields the exact same outcome: no left-hand brake lights when the right-hand turn signal is operating. (Just so we're clear, when the headlights are on and the right-hand turn signal is operating and the brake pedal is pressed, the left-hand taillights still stay illuminated but they are just at 'running light' intensity and not at 'brakes are on' intensity.)

The only function I didnít test at all was the 4-way flashers (hazards). Thatís on my list for tonight (if I can find some time).

Any ideas??? A very preliminary Google search suggested possible grounding issues but I don't see that as a valid explanation in this case given that all of the lighting on both sides (left and right) operates just fine in most cases. The ONLY combination that is goofy is that the brake lights DON'T work on the left-hand side if the right-hand turn signal is operating.

Ready? OK, go!!!! Let's hear your ideas because I'm puzzled. Thanks in advance!!!
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post #2 of 8 (permalink) Old May 23rd, 17, 07:39 AM
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Tom
 
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Re: Puzzling issue (related to brake lights and turn signals)

Don't know if I have a direct answer for you, other than the ground issues that you mentioned - these are quite often the root of many electrical issues. However, I will say this based on past experience - check the simple, stupid stuff first before you dig in too deep. Case in point: when I first got my 67 RS/SS, I had a lot of weird issues with the parking lights, brake lights, and turn signals. If I recall correctly, hitting the turn signal would actually make the dash lights blink in time to the flasher, and other strange things were going on. I scratched my head, drove myself crazy, and went as far as digging into the wiring in the steering column trying to find the cause. After banging my head against a wall for a while, I stumbled across the problem - the previous owner had installed 1156 bulbs in the taillight sockets instead of 1157's, which was allowing the current to back-feed to the instrument lamps. Sometimes it's the simple, stupid stuff. Good luck.

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post #3 of 8 (permalink) Old May 23rd, 17, 07:53 AM
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Re: Puzzling issue (related to brake lights and turn signals)

While you're doing your test, wiggle the socket in the taillight housing to see if anything changes. The slightest ground issue will do weird stuff like that.

I'd pull the sockets out of the taillight housing and clean the area where the socket grounds to the housing. Check the sockets themselves when you pull the bulbs out also.

That's a place to start anyway.

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post #4 of 8 (permalink) Old May 23rd, 17, 09:48 AM
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Al
 
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Re: Puzzling issue (related to brake lights and turn signals)

Agree - check the simple stuff first. You might even try swapping the t/s flasher with the emer flasher.

The LH brake light wire should be a 20ga yellow at the harmonica connector under the dash (clipped to the column?) - I'd check that with a test light.

The bad news is that the brake light circuit runs through the t/s switch which is a lot of work to replace.


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post #5 of 8 (permalink) Old May 23rd, 17, 10:57 AM
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George
 
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Re: Puzzling issue (related to brake lights and turn signals)

X2, check for output at the harmonica connector, it's probably your turn signal switch.
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post #6 of 8 (permalink) Old May 23rd, 17, 09:00 PM Thread Starter
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Steve
 
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Re: Puzzling issue (related to brake lights and turn signals)

Well, the facts are in: it's definitely looking like the turn signal switch is my culprit and it's probably been defective since the day I got the car a few years back.

Coming off of the yellow wire (left side turn signal / brakes) of the 'harmonica connector', here's what I get under various setups:
Turn signals off, brake pedal depressed: solid 12V (expected)
Left turn signal on, brakes off: pulsing 12V (expected, due to flasher)
Left turn signal on, brake pedal depressed: pulsing 12V (expected, due to flasher)
Right turn signal on, brakes off: 0V (expected since yellow wire is for left side brake/turn, not right side)
Right turn signal on, brake pedal depressed: 0V (and there it is; this should be 12V to apply power to the brake lights on left side)

By the way, doing these same tests on the dark green (right side turn signal / brakes) wire, I get all the expected readings in all cases and all of this holds true to what people behind me are seeing.

So, there's a new turn signal switch in my future. I'm guessing that to get the harmonica connector down the steering column, I'll need to lower the support bracketry that holds the steering column to the dash. Seems fairly straight forward. I've already pulled the steering wheel and all the guts down to the turn signal switch which, of course, LOOKS fine but obviously isn't.

Thanks for all the help, guys. To be honest, I did not mess much at all with the sockets or bulbs as I knew they were good. All the testing above proves where the problem is --- especially since all the rear lighting works in all but one scenario.
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post #7 of 8 (permalink) Old May 23rd, 17, 10:09 PM
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Al
 
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Re: Puzzling issue (related to brake lights and turn signals)

Bummer...

Tie a string to the harmonica connector so it comes up through the column when you remove the old switch, then use the string to help pull the new one back through
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post #8 of 8 (permalink) Old May 24th, 17, 03:28 PM Thread Starter
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Steve
 
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Re: Puzzling issue (related to brake lights and turn signals)

I was going to use an old length of wire to ease the installation but the concept is the same. Smarter, not harder. This isn't my first rodeo fishing wires --- be it in a car, a house, a boat, etc.

Last edited by sschultz2929; May 24th, 17 at 03:29 PM. Reason: left out a thought
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