Can someone help - electrical
Thread Starter
Melting Slicks
Joined: Feb 2007
Posts: 2,937
Likes: 163
From: OP Kansas
C2 of Year Finalist (appearance mods) 2019
Can someone help - electrical
I just received an email that I thought was a joke, so I called my friend and it was no joke, he was serious. He has a '75 Corvette, you can read for yourself:
Hey john. Long time since we last talked. I was wondering if you could help me with my 75. This problem just started. When I press the brake, the fasten seat belt light comes on and buzzes, the gas gauge goes to the right and the rear lights don't work. Any ideas
He just told me when he pulled his rear bulbs the buzzing stopped and the fasten seat belt light went out. I told him to check his grounds, but I don't know where to tell him to look. I know that when the gas gauge is grounded it will jump to full, but why would removing the bulbs prevent that?
Hey john. Long time since we last talked. I was wondering if you could help me with my 75. This problem just started. When I press the brake, the fasten seat belt light comes on and buzzes, the gas gauge goes to the right and the rear lights don't work. Any ideas
He just told me when he pulled his rear bulbs the buzzing stopped and the fasten seat belt light went out. I told him to check his grounds, but I don't know where to tell him to look. I know that when the gas gauge is grounded it will jump to full, but why would removing the bulbs prevent that?
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
When he says "rear lights don't work" we need more information as there are two separate circuits feeding the rear lights-- stop lights and marker lights- both have very different electrical paths.So, do the markers work and not the brakes or do the brakes work and not the markers or does nothing light at all?
OK, maybe a place to start or I'll just confuse things.
I consulted by Service Manual (but it for an '82 but my guess is that the wiring for is probably similar) and found a few things..
Rear light grounds are connected to the fuel gauge sender and then to the gauge itself then to the 20 amp "gauges" fuse
Seat belt warning light is connected to the 4-8 second timer, then to the buzzer then to the 20 amp "gauges" fuse
Tail lights are are connected to the stop light switch, then to the hazzard flasher then the Stop/Hazzard 20 amp fuse
My start would be to check the grounding of the rear tail light as when the bulb removed brings things back to "normal." And when the brake is applied and the rear lights are grounded through the gas sending unit causing the gas gauge to spike.
OK, maybe a place to start or I'll just confuse things.
I consulted by Service Manual (but it for an '82 but my guess is that the wiring for is probably similar) and found a few things..
Rear light grounds are connected to the fuel gauge sender and then to the gauge itself then to the 20 amp "gauges" fuse
Seat belt warning light is connected to the 4-8 second timer, then to the buzzer then to the 20 amp "gauges" fuse
Tail lights are are connected to the stop light switch, then to the hazzard flasher then the Stop/Hazzard 20 amp fuse
My start would be to check the grounding of the rear tail light as when the bulb removed brings things back to "normal." And when the brake is applied and the rear lights are grounded through the gas sending unit causing the gas gauge to spike.
Thread Starter
Melting Slicks
Joined: Feb 2007
Posts: 2,937
Likes: 163
From: OP Kansas
C2 of Year Finalist (appearance mods) 2019
Thanks for your replies. My friend fixed his problem, it was the ground that is connected to the frame in the rear. He said it was loose and a little corroded, so he cleaned it up and everything works now.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Exactly what I was going to say, had the problem myself some years ago on my '72 so I suppose your car is somewhat on schedule.....
Race Director
Joined: Jan 2000
Posts: 13,022
Likes: 2,265
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
Any time stuff does real goofy stuff like that...it is 99.99% of the time a ground.
JIM
JIM
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
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