1978 Z28 Turn Signal/Brake Light/Hazard Issue

Old Jul 15, 2013 | 06:09 PM
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Originally Posted by 1971BB427
I agree Damon. I would get a test light and start at the connector on the column, using the diagram I posted a link to. Check input 12v. power to ground. Then turn on the left and right turn signals, and check to see if the corresponding output from turnsignal sw. has power. After that pull the flasher slightly out of it's socket to check terminals with flasher still in place. Eventually it will lead to checking the sockets to body ground at the rear, and see if they illuminate the test lamp.
Automotive wiring is not complex, and especially with a wiring diagram to check various access points to see where the 12v. signal is lost.
OK, I'll start there. I'm gonna do my best. I positive the flasher is good, i just replaced it with a new one, and even with the old one I still have power to it. It's a two prong flasher and one side of it has power and the other doesn't so i'm assuming that it is a ground. I've got power everywhere in the front of the car with the exception being the turn signal switch is the only thing I haven't checked. Power at the turn signal switch wouldn't cause my loss of break lights though would it? I have power at the brake light switch and the switch is functioning properly because when i depress the plunger it shuts off my test light. I'm thinking the issue has to be somewhere in the wiring leading back to the lights.
 
Old Jul 15, 2013 | 09:45 PM
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Your brake lights are tied to the turn signal circuit, as that makes them override the brake lights when you're stopping and have the turn signal on. Your flasher does not ground the lamp to make them flash! You should have constant 12v. on the input terminal, and 12v. flashing output with turn signals on. There is a 2nd flasher for the 4 way flashers.
This is a basic wiring diagram that shows how the system works, with a toggle switch representing the turn signal switch:


As you can see the flasher connects to a common on the turn signal switch, so it powers either side. Ignore the brake light system wiring in this diagram, as it uses a separate wire and lamp for the brake lamps. GM doesn't do their's this way, and the same lamp that flashes turn signal, also is used for brake lights by incorporating the brake switch ahead of the flasher.
 

Last edited by 1971BB427; Jul 15, 2013 at 09:49 PM.
Old Jul 16, 2013 | 05:08 PM
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Thanks for the help everyone. 1971BB427, i started tracing wires from the column back and when doing so I found a few wires that were basically almost fused themselves together. I cut out the bad parts and put the wires back together and everything works! I knew it had to be something within the wiring based on everything having power. I appreciate all the help and the electrical education I got out of this. It was something that I could have very easily looked right past again because it was very hard to tell where they had fused themselves. Thanks again everyone!
 
Old Jul 17, 2013 | 09:25 AM
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Glad you got it!
 
Old Jul 20, 2013 | 10:05 AM
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I had the same problem with a 78 and79 z28 I had. It ended up being a couple of wires were broken at the fuse box my clutch pedal kepped hit the wires until they broke and the wires didn't look broken until I started moving them when I was checking out the problem.
 
Old Jul 23, 2013 | 03:45 AM
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You know, I never throught that clutch pedal hitting them could have been an issue! Either way they are out of the way of it now so hopefully I won't have any further issues. Thanks again everyone.
 
Old Jul 24, 2013 | 03:58 AM
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Was the clutch pedal hitting the wires the problem?
 

Last edited by frankzlt1; Jul 24, 2013 at 04:00 AM.
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