How to troubleshoot a brake light problem - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

 
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post #1 of 15 (permalink) Old Mar 4th, 09, 07:56 PM Thread Starter
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How to troubleshoot a brake light problem

Can anyone tell me how to troubleshoot a non working brake light issue? I know that the E brake and the master cylinder will turn it on but I have nothing at the Ebrake pedal and the rear MC went dry and no light ever came on for that. I did swap the bulb with one I knew that worked and still nothing.
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post #2 of 15 (permalink) Old Mar 4th, 09, 08:12 PM
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Re: How to troubleshoot a brake light problem

did you check the switch at the ebrake to make sure that it was working?

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post #3 of 15 (permalink) Old Mar 4th, 09, 08:28 PM
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Re: How to troubleshoot a brake light problem

There should be a tan wire on the brake block under the master cyl, unplug and ground this wire to test the light circuit. The key must be on of course. The emergency brake switch is the same color wire, ground it at the E brake to test that.
David

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post #4 of 15 (permalink) Old Mar 4th, 09, 08:39 PM Thread Starter
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Re: How to troubleshoot a brake light problem

The e brake switch is very rusty and I could not pull the wire out of the rear but will try again.I'm also missing the paddle for the e brake switch.
I know where the tan wire is to the MC, when I ground it the bulb should light correct?
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post #5 of 15 (permalink) Old Mar 5th, 09, 12:23 AM
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Re: How to troubleshoot a brake light problem

Yes, the circuit works just like your dome lamps.
David

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post #6 of 15 (permalink) Old Mar 5th, 09, 04:30 AM
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Re: How to troubleshoot a brake light problem

With both switches open (wire disconnected or park brake switch taped open since the paddle is gone), you should be able to measure battery voltage at the end of the tan wire to ground if the bulb is good, no broken filament or broken socket ear.

As David suggests, touch the wire to ground and light should light with the ign key on IGN.

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post #7 of 15 (permalink) Old Mar 5th, 09, 04:11 PM Thread Starter
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Re: How to troubleshoot a brake light problem

With the cars ignition switch in the on position I pushed open the parking brake switch and had a reading of 10.5 volts. Then I pulled the bulb the right side prong had 10.5 and the left side prong had about .50 or something like that. I could not get the hood open because the car cover is stuck/frozen to the hood. I will find out what the reading is at the M/C soon. Do these readings sound good? I still cant get the tan wire out of the park brake switch.

Last edited by bigsteve; Mar 5th, 09 at 05:53 PM.
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post #8 of 15 (permalink) Old Mar 5th, 09, 06:12 PM
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Re: How to troubleshoot a brake light problem

If you have battery voltage at the tan wire at the p/brake switch with the switch pushed open, this is good.

With the switch closed, the light should light if the switch is making a good ground connection.
If you have 0.5 volts at the socket key, then the p/brake switch being closed is not making a good contact with ground - high resistance.

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post #9 of 15 (permalink) Old Mar 5th, 09, 06:49 PM
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Re: How to troubleshoot a brake light problem

Steve,
I'm going to move this thread to the Electrical section, it's more appropriate there and you may get more help.

10.5 volts is a BADLY DISCHARGED battery, or resistance in the system. Check at your battery and see what voltage is there, or check the cigarette lighter voltage if you can't open the hood right now.
David

STATE OF CHARGE ----VOLTS engine off.
100%---------12.66
75%----------12.45
50%----------12.24
25%----------12.06
0%-----------11.89

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post #10 of 15 (permalink) Old Mar 6th, 09, 03:28 AM Thread Starter
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Re: How to troubleshoot a brake light problem

The park brake switch contact is very rusty and where the wire is stuck and wont come out I could have a bad contact their.

I actually had 10.5 volts on the right side of the light bulb socket.

The battery is getting old and car has sat for many years and cold outside so , i'll check it after work today.

Do I need to take off the E brake assembly to remove the switch?

Last edited by bigsteve; Mar 6th, 09 at 04:07 AM.
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post #11 of 15 (permalink) Old Mar 6th, 09, 05:02 AM
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Re: How to troubleshoot a brake light problem

Steve, as a generic test procedure, you need an ohm meter and the Camaro wiring diagram. you need to test each leg of a circuit against ground to see if you are getting the 12 volts. If you do not get 12 volts, you need to backtrack the circuit until you do and follow it to find the break. A LOT of common problems on Camaros are caused by poor grounds, so you check that first. On old cars its rust, on newly restored cars its paint layers. have fun!

You should not have to remove the e-brake switch to test, just poke the ohm meter leads on the switch.

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post #12 of 15 (permalink) Old Mar 6th, 09, 03:48 PM Thread Starter
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Re: How to troubleshoot a brake light problem

Checked the battery voltage and it at 11.5, today I had no voltage at the e brake switch or the M/C wire.
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post #13 of 15 (permalink) Old Mar 6th, 09, 07:34 PM
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Re: How to troubleshoot a brake light problem

You may not have any voltage going though the drvr side bulkhead connector on the tan wire.

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post #14 of 15 (permalink) Old Mar 7th, 09, 03:47 AM Thread Starter
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Re: How to troubleshoot a brake light problem

How many grounds are their, battery and body grounds?
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post #15 of 15 (permalink) Old Mar 7th, 09, 05:17 AM
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Re: How to troubleshoot a brake light problem

Steve, those are the ground feeders (bat to engine, engine to body, body to subframe), Generally each wiring harness has a ground wire, some like the main dash harness have a couple. So in addition to making sure you body is grounded to bat, you need to make sure harness has a good ground to body.

Kevin


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