Hey guys,

My "brake" light on my dash won't turn off when the car is on and the parking break is down.

Typically after I drive my car, or any stick for that matter, I get it to where I want to park it, apply the parking break, and turn off the car. The car remains in gear, as another precaution to rolling, but I try to use the parking break to hold any rolling weight so it is not on the gears.

Now, when I get in and start the car the break light won't turn off. Any suggestions?

Thanks.

 

Have you checked the switch on the brake lever in the console? It's a ground switch--unhook the wire and see if light goes out.

 

Don't know what your vintage car has but my switch on the parking brake is a spring loaded affair and it would not be out of line for it to fail. It's easy to replace and not expensive. If you have a proportioning valve it also could be that though I'd think the p.b. switch would be more likely. In my 76 the proportioning valve has a pin in the middle on top which a female connector slips over to connect. When the proportioning valve has any air in the brake lines instead of being centered the assembly inside the p.valve slides either forward or back. When it does so the male pin from above drops due to gravity and makes contact with what must be the ground side of the car and the dash red brake light goes on. When we had another problem with my p. valve when I first got the car the new one purchased from Zip for about $100 worked to brake the car but the light would never shut off so they sent another one. It worked for about six months then the light started to sporacically come on. Could be the tiniest bubble in the line somewhere that worked loose but it's all new calipers and pistons, all new hoses, the third new master cylinder which came from a supplier which also failed right out of the box and the brakes do not lose fluid, leak and are perfect. My conclusion is that the five or six inch long brass proportioning valve on my 76 was early days design and it just way, way too sensitive. We've bled the brakes enough times and I'm familiar enough with the car that it isn't work continuing to screw with so about two months ago I just pulled the female wire off, filled it with dielectric grease and parked it. End of the darned light problem. I watch the brakes and check the mc fluid to be sure it's okay and the sensing wire has nothing to do with whether or not the p valve would actually work to block off either front or rear set if the other set lost pressure so I can't see any downside to it. Most persistent problem I've had with the vette and since it only comes on with contact at least to my above understanding it does no harm to unhook it.

I haven't taken one apart or seen a detailed diagram but from what I can tell that is my understanding of it. It is a safety item and not bad but annoying if that light starts to go on.

Hope this assists you in figuring it out. The AIM has drawings of where the little spring loaded parking brake switch is under the console cover.

Lance P.

 

Questions like this are tough to answer when the '72 is covered and all buttoned up for the winter. Can't run out and look at the dash, so I'll have to play it from memory. If your emergency brake light on the center panel won't go off, then you'll have to remove the emergency brake console cover, first. Under it you'll find a switch connected to the e-brake mechanism that you can adjust in or out by moving a nut on the switch. That should take care of your light if it's the e-brake light.
On the other hand, if it's the brake light that's in your speedo or tach (don't remember which one right now) then you have a hydraulic problem with your brake system. I hope it's the first one! Good luck!
Duane

 

Well, unless the light on the dash will illuminate for both problems, then it is just for the parking break. The light came on when I applied the parking break. But up until now, it always went off when I put the lever down (disengaged the break).

 

It sounds like the small switch on the brake handle under the console cover. I'll attach a photo of the switch which is for 68-82 Vettes. It screws to the frame and when the handle comes up or down the spring either frees it or is compressed but when not in contact that switch can move back in forth a little and if the switch is original it is easily possible that the spring doesn't hold it correctly and needs replacement. I replaced mine.

Anything else it's a warning from a proportioning valve that you have air in your brake lines or something else..see the discussion abover re: p. valves as it applies to my 76.

Lance P.

 

this is the valve for a 78-82 and it still has the brake warning fixture in the middle on top but the connection is slightly different than on my 76 which may mean they fixed the sporadic nature of it. My male connector is taller and the newer model appears different. Inside the p valve which is maybe five inches long I'm sure the mechanism is likely to be similar but it was such early days they may have improved regularly. Wish I had seen a drawing but haven't found one yet.

I think it's just the p brake original switch with the spring that needs replacing from your comments and far less expensive to do than the p valve to start with. When my p valve failed it locked the back brakes temporarily so failure mode was quite different and when it did somehow the brake warning light did not come on.

Lance P.

 

proportioning valve for 78-82

 

p valve for 78-82

 

Hey Lance,

I pulled back the rubber flaps for the PB and I remember seeing that switch, but the round end wasn't touching anything. I will play with it some, but just for my knowledge...does the end need to be touching something for the light to go off or is it vise versa?

 

Darned if I can remember. Check the AIM to see if it shows there. Pulling the p.b. handle up did one thing to it and forced contact and putting it down reversed the action. what I remember is that black central part literally bouncing forward and back inside that spring when I think the spring is supposed to hold it stable so it won't touch when it is not supposed to but over 35 years I'd guess the spring has weakened enough that it simply needs replacement. I did mine and the new one was ever so slightly more stable. It isn't what you'd call a solid, well made, substantial switch but one that the core sort of moves around inside that spring mechanism. I had photos of the old one originally and comparing it to the new one the differences were small but it resolved a problem related to the pb handle and on/off with that. I've spent more time on brakes and brake warning lights than anything else on my corvette! Will post aim of 76 switch in place in a second

 

here it is for a 76

 

I haven't got my AIM out yet, but I wanted to show what I found based on the diagram given above. (I was already in the car for something else)



As you can see in the pic, that little spring and bar are not touching anything while the handle is down. This may be the issue. I will try to get the AIM out later today, but if anyone has some advice to offer in the mean time, go ahead.

 

the switch when not in the car is parallel to the bracket and yours is angled which might indicate the spring has lost its resilency and hence, its function.

Did you move the black center while the engine was on to see if the light goes on or off? Might be a cheap way to test the spring to see.

Lance P.

 

 

note the little metal insert in the black carrier...I think that is supposed to touch the frame of the switch by pressure and when the black button is pushed it pushes it past the frame and no contact is made and no light comes on. If I remember right looking closer the little metal insert in my black part was no longer holding itself tightly enough with outward pressure to always make contact in the position shown above so it kept giving weird lights. Replaced, end of debate...light only comes on when parking brake comes on.

lance p.

 

Ya, I tried with my finger, but I couldn't get any leverage on it. I will need to play with it later.

Do you know the part number for this? My Parts and illustration manual is at my GFs place.

 

Nope...go to zip.com who supplies them among many other vette suppliers.

http://www.zip-corvette.com/?iorb=47..._campaign=BROI

 

Adjust the switch on the parking brake handle before you start fretting over brake pressure differential switches.