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Brake lights not working

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Old Mar 12, 2011 | 04:14 PM
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Default Brake lights not working

Sorry for starting yet another thread on the brake lights, but I have searched and could not find anything that helped.

Turn signals work.. hazards work fine
Brake switch is fine (confirmed 12V at both sides when pedal is pushed)
Bulbs are good (used ohm meter)
Ground is good on socket (used ohm meter)

On the harmonica connector, I disconnected and attempted to jumper the white to green or yellow.. Lights do not come on when pedal is pushed.

I have 12V on the white wire on the harmonica connector when the pedal is pushed.

Are there any other harness connectors that I can look at? I'm thinking my prob is a break in the yellow and green wires on its path to the real lights??? Or would this keep my hazards and turn signals from working also?
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Old Mar 12, 2011 | 04:43 PM
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im not sure what year your car is but would a 71 wiring diagram help ?
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Old Mar 12, 2011 | 04:53 PM
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I should have mentioned that. It's a 69, and I have a diagram. It shows a connector at the top of the page. Looking at it with fresh eyes, it appears same yellow or green wire supply power for stop and turn signals.
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Old Mar 12, 2011 | 05:45 PM
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There is another connector for the rear harness under the dash at the A pillar.
But you are correct, if the turn and hazards work as you say, then the wiring, grounds and bulbs are good.
Pretty well leaves the turn switch.
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Old Mar 12, 2011 | 06:29 PM
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Thanks. Not sure why my jumper of white to green and yellow did not work. Possible I did not have good contact while pushing the pedal. Or my helper that was watching the lights was looking at the wrong light


I hate to tear apart the column without confirming the switch is bad, but it's starting to look like that.
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Old Mar 12, 2011 | 06:57 PM
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You can just plug in a good turn switch without installing it, just to test,
or run 12v directly from the battery to the rear harness side of the harmonica yellow and green.
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Old Mar 12, 2011 | 08:18 PM
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http://www.powerprobe.com/powerprobe/Home.html
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Old Mar 12, 2011 | 08:32 PM
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Originally Posted by terry82
What the heck is that ?
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Old Mar 12, 2011 | 08:53 PM
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it will help you find electrical shorts .its not cheap but it will help you find the problem.
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Old Mar 12, 2011 | 08:54 PM
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I think that I am going to order a turn signal switch, and do as suggested to try connecting it before installing. Looking at the symptoms and the wiring diagram, I am betting my attempt to jumper had something wrong.

Should I order a horn retaining clip also? I've seen the the get brittle and would hate for my day to be ruined by a $10 part

Guessing Ecklers is best place to get the switch?
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Old Mar 12, 2011 | 10:46 PM
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I plugged a new turn signal switch into my car and the brake lights still didn't work. I should have replaced the $7 brake light switch first.

If your column hasn't been apart in years, I would suggest having a new c-clip retainer to replace the original which will most likely crumble into several pieces when you try and remove it. Dealerships want something like $18 for it. It is available through most Corvette suppliers for a lot less. BTW, the plastic retainer is also an insulator that prevents the big telescoping spring from touching metal and your horn blowing all the time.

I just noticed that you have a 1969 (and I assume a T&T column). Standard (non-adjustable) columns do not use a c-clip retainer. Also, there is a good chance that your 1969 T&T column (that year only) may also not have a retainer. I believe that your toothed locking plate may have a rubber cover (or pad) on the plate that may act as an insulator in place of the retainer.
Jim

Last edited by Jim Shea; Mar 13, 2011 at 10:58 AM.
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Old Mar 13, 2011 | 11:56 AM
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Huge thanks to all that suggested trying a new brake switch.. I was reluctant since the prior owner had a new switch..

Since I was getting 12V at the harmonica connector when the peddle was pushed, I was positive the switch was good.

Well - I WAS WRONG!!!. Picked up a new switch today, plugged it in and the brake lights started working again..

I decided to ohm out the old switch, and guess what.. it was measuring 600 ohms when closed. Simple ohms law was playing into the equation here and the brake switch was consuming the amps in the serial circuit it has with the lights. The new switch measured 1 ohm when closed.. This also explains why my white to green/yellow jumper was not working

So, lesson to later folks.. Measure the resistance on the switch.. even if the voltage looks good

Glad to have this one fixed!!!
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