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Brake Lights

Vette79

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1979 L-48 Black Coupe
My brake lights on a 79 are on when battery is connected. No other exterior lights are on except the brake lights. Any idea what the problem might be? When I use the turn signal for left or right the corresponding brake light goes out. This is not the parking lights but the brake lights. Thanks for any help provided.
 
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7,246
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Washington, Michigan
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'67 Marina Blue Convertible
Your brake light switch needs to be adjusted (up under the dash, about 4" below the brake pedal's pivot point). The turn signal switch automatically shuts off the brake light on the side that faces the direction you're turning, as it uses the same filament in the bulb that the brake light uses.

:beer
 

Vette79

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1979 L-48 Black Coupe
Perfect. That was the problem. I figured it out on my own and then read your thread. Thanks John for responding. What a pain to get up under there and adjust. All I have left now to figure out is the Rear Defrost and Cigarette Lighter. They don't work but everything else does. Any suggestions?
 

Vette79

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1979 L-48 Black Coupe
Anyone have a fuse panel diagram so that I can troubleshoot the Rear Defogger and Cigarette Lighter? Any other ideas to help resolve my issue would be great. Thanks, Jeff.
 

6880 Mike

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The Bluegrass State
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1968 convertible; 1980 L-82
Anyone have a fuse panel diagram so that I can troubleshoot the Rear Defogger and Cigarette Lighter?...

Do you have an owner's manual for your '79? The aftermarket providers carry reproductions. Fuse panel and a listing of the fuses/breakers are in the owner's manual.

If memory serves, there is a relay for the RW defogger in addition to a fuse.

:)
 

Vette79

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1979 L-48 Black Coupe
The owners manual was not very helpful at all. Wanting to know what fuses are associated with what devices. Are there seperate Relays or Circuit Breakers involved. Maybe a bad ground. Cigarette Lighter and Rear Defogger left to troubleshoot.
 

duke94

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277
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Ann Arbor, MI
Corvette
71' convert and 78' both Red
The owners manual was not very helpful at all. Wanting to know what fuses are associated with what devices. Are there seperate Relays or Circuit Breakers involved. Maybe a bad ground. Cigarette Lighter and Rear Defogger left to troubleshoot.

Here's my 78', should be the same as 79'

78reardefog.jpg
 

Vette79

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Millersville, MD
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1979 L-48 Black Coupe
Duke, thanks so much for this. Very helpful. Did this come out of the shop manual? Might you have the same diagram for the cigarette Lighter? Thanks again for the help...Jeff.
 

angry planet

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Sep 19, 2004
Messages
25
Location
Dallas
Corvette
1968
Same problem with brake lights...

"Your brake light switch needs to be adjusted (up under the dash, about 4" below the brake pedal's pivot point). ."


Can someone explain what this means / give a little more detail?

What is the pivot point? What does the switch look like and how do I adjust it?

Thanks a ton
 

Vette79

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1979 L-48 Black Coupe
Follow the brake pedal up til you see a black switch that has two sets of wires attached to it. It appears to be threaded with like a push button at the end that the brake pedal comes in contact with to activate the switch. While pushing on the brake pedal to give you room to adjust the switch, wiggle and push the switch gently in toward the front of the car so that the switch can operate with the movement of the brake pedal. To verify that your problem is the switch, if you can, just push in on the button/switch to see if the brake lights go off. If they do then try and follow the directions given. I will check this post later tomorrow and if someone else does not give a better answer or pic then I will take a pic for you later. It is a pain to crawl up under the dash to adjust this switch. Hope this helps and good luck.
 

angry planet

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Dallas
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1968
Follow the brake pedal up til you see a black switch that has two sets of wires attached to it. It appears to be threaded with like a push button at the end that the brake pedal comes in contact with to activate the switch. While pushing on the brake pedal to give you room to adjust the switch, wiggle and push the switch gently in toward the front of the car so that the switch can operate with the movement of the brake pedal. To verify that your problem is the switch, if you can, just push in on the button/switch to see if the brake lights go off. If they do then try and follow the directions given. I will check this post later tomorrow and if someone else does not give a better answer or pic then I will take a pic for you later. It is a pain to crawl up under the dash to adjust this switch. Hope this helps and good luck.

This was a huge help: I found the switch and jammed something between the switch and the brake pedal to shut off the lights for now.

I still don't see how to adjust it though... visibility is near zero up in there and I don't know what I am looking for anyway :) I wiggled and pushed the switch around as described above, but I wasn't really changing anything. Can someone give a little more detail?
 

Vette79

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1979 L-48 Black Coupe
The threaded portion of the switch is inserted through a hole right before the brake pedal arm. Hard to see. No need to turn the switch to threaded through the hole. Just push on it and wiggle it til it moves forward enough through the hole so that the switch is engaged when the brake pedal is not in use. Again, you have to push on the brake pedal so that you can push and wiggle the switch through the hole. Only the first few threads of the switch should be required to be through the hole for the switch to work. Let us know how this works out for you.
 

Evolution1980

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Cleveland, Ohio
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ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
vette79, are you running a manual or a automatic trans?

If you are running an automatic trans, then that switch also controls your torque converter lock-up solenoid. Whenever the brake is depressed, it cuts the 3v (?) signal going to the solenoid and unlocks it. If you have an auto trans, you can expect better cruising RPMs now as well! :cool
 

Vette79

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Jan 23, 2007
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Location
Millersville, MD
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1979 L-48 Black Coupe
I had no idea. My brake lights were constantly on and I troubleshot it down to this switch. I think I knocked it lose when I was checking the fuses initially. Is there a proper adjustment for this switch? I just pushed the switch back in until the lights went out when the brake pedal was not depressed. Should I adjust it further? Thanks so much for the info.
 

Vette79

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Millersville, MD
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1979 L-48 Black Coupe
I have an auto trans. How does this switch operate the torque converter lock-up solenoid? It seems like a simple switch to turn brake lights on or off. When cruising, the switch is depressed due to the brake not being used and the brake lights off. So could you explain how all this works? Thanks, Evolution 1980. Learning something new so please bear with me...
 

Evolution1980

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ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
I had no idea. My brake lights were constantly on and I troubleshot it down to this switch. I think I knocked it lose when I was checking the fuses initially. Is there a proper adjustment for this switch? I just pushed the switch back in until the lights went out when the brake pedal was not depressed. Should I adjust it further? Thanks so much for the info.
It should rest just behind the pedal. Maybe 1/16th - 1/8th of an inch. I don't know if there's an exact OEM measurement, but basically the switch should engage as soon as the brake pedal is depressed even just a hair.

I have an auto trans. How does this switch operate the torque converter lock-up solenoid? It seems like a simple switch to turn brake lights on or off. When cruising, the switch is depressed due to the brake not being used and the brake lights off. So could you explain how all this works? Thanks, Evolution 1980. Learning something new so please bear with me...
The switch also acts as a breaker to the 3v circuit that goes to and engages the lock up solenoid. (Also referred to as a Torque Converter Clutch ("TCC") solenoid.) When the 3v signal engages the TCC, the TC will 'lock' and spin at the same RPM of the engine, thus no longer using "torque multiplication". This is like having a manual tranmission of sorts, as the transmission is directly connected, or 'locked', to the engine. What would happen if this stays locked is the same thing that happens if you don't use the clutch when coming to a stop...the car would stall because the transmission would physically stop the engine's rotation. When you hit your brake, that switch behind the pedal breaks the 3v circuit thus releasing that "lock up".

It's not uncommon for the actual solenoid to go bad. Nothing 'bad' happens inside the transmission except that you don't get that 1:1 lock. Most people may not even know that their's isn't working until it happens to be noticed by someone diagnosing transmission problems or they just happen to notice that their RPM's in their highest gear are ever so slightly higher than they used to be.

Besides dropping the pan and checking the solenoid operation with a voltmeter, one easy way to check is to go out on the highway. Do about 60mph or so, as long as you are in your top gear. Ever so gently apply the brake. It should only be enough to trigger the switch/brakelights, but not actually engage the brakes. You should notice your RPM's jump up a couple hundred RPM's. You won't likely feel anything because the brakes aren't actually engaging, but you'll see it in your tach as the lock-up releases and the TC goes back to using toque multiplication.

When I was troubleshooting problems with my original TH350, that's when my mechanic noticed it wasn't working. So we installed a diagnostic light on my dash. If I have the 3v going to my solenoid, the light is on. When I lose that 3v, the light goes off. Thus, when I hit my brakes, that light goes off. Now I'll know for sure if that solenoid ever goes bad again. It's overkill, but it was primarily meant to be simply a troubleshooting light. I ended up just leaving it there. :)

If you are hungry for more info, you can always ask here or google it. You should be able to find a couple different references.
 

Vette79

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1979 L-48 Black Coupe
Great information Evolution1980!!! I had the switch in a little to far I think so I readjusted and will take it out tomorrow for a test drive. My original transmission was just rebuilt with a shift kit installed. Today it seemed a bit sluggish in response during a test drive today but that is probably due to it sitting for awhile or not warmed up fully. I managed to get my cigarette lighter working and now need to troubleshoot the rear defogger. Afterwards, I want to look at the stock car alarm. Not really sure were to begin with that. Trying to buy a shop manual to assist. Anyways, thanks so much for the explanation. I really appreciate the response.
 
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South Dakota
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76 Coupe
I was going to suggest a box of kleenex and a Bic, but since you got your lighter fixed, guess I just let it be...............:D


' I know nothing!!
 

Evolution1980

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ZZ4, 700R4, Steeroids rack & pinion, VB&P Brakes
...now need to troubleshoot the rear defogger.
Mine stopped working for like three weeks, and then it just started working again. :confused
Anyways, I think there's a fuse in block with all the other fuses, and a relay somewhere back by the battery. I can hear my relay click when I turn the rear defroster on/off. Someone else can tell you for sure.
 

Vette79

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Jan 23, 2007
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Millersville, MD
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1979 L-48 Black Coupe
LOL. I know I don't really need the cigarette lighter but it just bothers me that it doesn't work. Kinda like the rear defogger. I will probably never use it but it's the fact that it doesn't work yet it should. Besides it is a great excuse to get away from the wife and kids for a little bit. Are you still thinking about selling your Vette?
 

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