Turn Signal & Brake Light Problem - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

 
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post #1 of 13 (permalink) Old Aug 11th, 07, 5:06 PM Thread Starter
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Turn Signal & Brake Light Problem

My passenger side rear brake light does not work and my passenger side rear turn signal also doesn't work. The drivers side brake light and tail lights on both sides work ok, the turn signals in the front, left rear and dash indicators work ok also, just the right rear brake and turn signal don't work. I have a receipt from the previous owner saying that the turn signal switch was already replaced, i replaced both flashers and all bulbs. Any suggestions?
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post #2 of 13 (permalink) Old Aug 11th, 07, 6:23 PM
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Re: Turn Signal & Brake Light Problem

What kind of vehicle?

You can use a test light or meter to see where you have voltage and where you don't have voltage on that wire.
I would probably check at the bulb socket first, then at the steering column.
The turn signal switch turns off each brake light when it turns ON that side blinker.
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post #3 of 13 (permalink) Old Aug 11th, 07, 8:37 PM Thread Starter
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Re: Turn Signal & Brake Light Problem

Its a 1970 Monte Carlo, do you know what color the wire is for that circuit? I am very bad at reading wiring diagrams. Also since the tail light works ok doesn't it mean that its getting 12v at the bulb socket?
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post #4 of 13 (permalink) Old Aug 11th, 07, 10:57 PM
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Re: Turn Signal & Brake Light Problem

Don't know about Monte Carlos but probably the same as Chevelle - Dark Green.

Basically that bulb is two bulbs in one (duel filament) so the taillight power goes to one filament and the stop/turn wire goes to the other filament (which is brighter) and of course they share the common ground through the socket.
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post #5 of 13 (permalink) Old Aug 12th, 07, 4:51 PM Thread Starter
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Re: Turn Signal & Brake Light Problem

ok, this is what I have so far: I checked for 12v on the dark green wire at the column on both sides of the connector, when right turn signal is on the test light blinks on and off - ok. I checked in the trunk at the connector and the dark green wire has no voltage at all with the right rear turn signal on, I manually applied 12v to the dark green wire and the right rear turn signal & brake light go on, this tells me that the bulb sockets & ground is ok at the right rear? Where else should I check? Does anyone know the correct part number for the turn signal flasher? The guy at kragen just gave me the same flasher as the one on the fuse panel(emrgency lights) "552" and I noticed it had a different number than the original which was "532" I wonder if that could be it?
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post #6 of 13 (permalink) Old Aug 13th, 07, 10:42 AM
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Re: Turn Signal & Brake Light Problem

Quote:
Originally Posted by Marxx View Post
ok, this is what I have so far: I checked for 12v on the dark green wire at the column on both sides of the connector, when right turn signal is on the test light blinks on and off - ok.
That wire should also be hot with the turn signal lever off and the brake pedal depressed.
If not, there is a problem in the turn signal switch since the other side brake light is working.

Quote:
Originally Posted by Marxx View Post
I checked in the trunk at the connector and the dark green wire has no voltage at all with the right rear turn signal on, I manually applied 12v to the dark green wire and the right rear turn signal & brake light go on, this tells me that the bulb sockets & ground is ok at the right rear? Where else should I check?
see above ^
Check it at the harness under the back seat also.
Quote:
Originally Posted by Marxx View Post
Does anyone know the correct part number for the turn signal flasher? The guy at kragen just gave me the same flasher as the one on the fuse panel(emrgency lights) "552" and I noticed it had a different number than the original which was "532" I wonder if that could be it?
If the flasher was bad it would effect all four turn signals, not just one bulb.
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post #7 of 13 (permalink) Old Aug 13th, 07, 7:50 PM Thread Starter
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Re: Turn Signal & Brake Light Problem

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Originally Posted by Dean View Post
That wire should also be hot with the turn signal lever off and the brake pedal depressed.
If not, there is a problem in the turn signal switch since the other side brake light is working.
With the right turn signal off and the brake pedal pushed down, there is 12v on the dark green wire, once I let go of the brake pedal there is no 12v. Is this ok or a sign of the switch going bad? Also I checked the connector next to the fuse panel (picture below), I was thinking that thes is where the harness goes all the way to the back? And noticed that the dark green wire on this connector doesn't have 12v at all with or without the turn signal on?? I'm confused, thanks for all the help so far....

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post #8 of 13 (permalink) Old Aug 13th, 07, 10:16 PM
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Re: Turn Signal & Brake Light Problem

OK, the wire should have power with the turn signal off and the brake pedal depressed and no power when you let off the brake.

It should also have power (blinking on and off) when the turn signal is turned on.

Now trace the wire and find out where it has power and where it doesn't have power.

I suspect it doesn't have power somewhere under the carpet
The flat harness runs under the carpet/back seat BUT if that connector in the picture IS the harness going back and it has no power there then the problem must be in that connector.
Check both sides of the connector.
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post #9 of 13 (permalink) Old Aug 17th, 07, 12:03 AM Thread Starter
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Re: Turn Signal & Brake Light Problem

Ok so heres the deal so far, I have power at the turn signal connector at the column when the brake pedal is down and blinking with right turn signal switch set (turn signal switch is good). I have no power at the connector in the picture above which is the last connector before the harness runs out to the back, so I applied 12v to the dark green wire at the connector pictured above and the right rear turn signal/brake light comes on (this tells me the the harness is ok all the way back to the bulbs, right?) So I am assuming that the break in the wire is between the turn signal switch at the column and the harness connector next to the fuse box in the dash harness somewhere, does this sound right to you guys? Thanks for all the help so far....
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post #10 of 13 (permalink) Old Aug 17th, 07, 3:06 PM
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Re: Turn Signal & Brake Light Problem

I have the exact same problem with my 72 chevelle. Same problem,same side. I was told its the turn signal switch. I pulled the back seat and checked the green wire too. The only difference is with my car I get a very small amount of voltage to the green wire(at the tail light) and when I unhook the ground to the tail light harness the tail light/brake lights go dim..But they both work.

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post #11 of 13 (permalink) Old Aug 17th, 07, 5:17 PM
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Re: Turn Signal & Brake Light Problem

Quote:
Originally Posted by Marxx View Post
Ok so heres the deal so far, I have power at the turn signal connector at the column when the brake pedal is down and blinking with right turn signal switch set (turn signal switch is good). I have no power at the connector in the picture above which is the last connector before the harness runs out to the back, so I applied 12v to the dark green wire at the connector pictured above and the right rear turn signal/brake light comes on (this tells me the the harness is ok all the way back to the bulbs, right?) So I am assuming that the break in the wire is between the turn signal switch at the column and the harness connector next to the fuse box in the dash harness somewhere, does this sound right to you guys? Thanks for all the help so far....
Sounds like you're on the right track.
If the wire has power at one place and does not have power at another spot, then it has to be broken in between somewhere.
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post #12 of 13 (permalink) Old Aug 17th, 07, 5:21 PM
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Re: Turn Signal & Brake Light Problem

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Originally Posted by VMXRACER View Post
I have the exact same problem with my 72 chevelle. Same problem,same side. I was told its the turn signal switch. I pulled the back seat and checked the green wire too. The only difference is with my car I get a very small amount of voltage to the green wire(at the tail light) and when I unhook the ground to the tail light harness the tail light/brake lights go dim..But they both work.
The electricity does some strange stuff when there is not a good ground.

Power to one filament on a double filament bulb can try to get it's ground from it's other filament because voltage is induced from one filament to the other.
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post #13 of 13 (permalink) Old Aug 17th, 07, 5:29 PM
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Re: Turn Signal & Brake Light Problem

Last week I sprayed the turn signal switch with contact cleaner and checked it today..seems to be fine now. Looks like a turn signal switch is in my future though. Thanks for the help Marco and Dean.

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