Brake warning light on...dim - Team Camaro Tech
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post #1 of 7 (permalink) Old Sep 27th, 14, 08:09 AM Thread Starter
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Brake warning light on...dim

I'm posting in Electrical & Wiring because I'm pretty sure this problem has nothing to do with my brake functioning.

'67 RS with factory drum/drum and factory MC/brake line routing and setup. I've determined that the speedo/gauge cluster was likely swapped out in the early '80s to provide the correct warning lights to match the console floor gauges that we're also added to the car (also to add a lower mileage odometer!)

My brake warning light has started to come on VERY dimly seemingly on cooler days when the car is cold. Sometimes it will go off completely but it never comes on bright. Sometimes it is so faint that I'm not sure it is on but in the dark, it clearly is. The bulb seems to be fine because it comes on fully bright when I push the e-brake pedal. Brakes are normal and working fine and there is correct amount of fluid in the MC and no leaks anywhere. I would expect flickering from on to off if there was a problem with brake pressure not this faint glow. Any ideas?
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post #2 of 7 (permalink) Old Sep 27th, 14, 09:08 AM
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Re: Brake warning light on...dim

Check the pressure switch on the brake valve and or your fluid.


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post #3 of 7 (permalink) Old Sep 27th, 14, 09:25 AM Thread Starter
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Re: Brake warning light on...dim

Fluid is fine. I'm not sure what you mean by check the switch. I will test to see if the dim light goes out by removing the brown wire from the switch. But if the switch is making a connection due to a pressure differential between front and rear lines, shouldn't the light come on fully rather than very dim?
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post #4 of 7 (permalink) Old Sep 27th, 14, 09:52 AM Thread Starter
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Re: Brake warning light on...dim

OK. Working on this now. On Brians suggestion, I double checked the fluid and started to suspect the switch. Fluid is still fine. I turned the key and the light came on brighter than it has but still not nearly as bright as the e-brake activation. I disconnected the tan wire from the switch and the light went out. Reconnected it and the light came on. Started the car and the light stayed on. Again, still not very bright. Drove back and forth and hit the brakes a few times. Light stayed on. Pumped the brakes and light stayed on. Turned ignition off and then restarted the car and light went off!! Is it something in the ignition switch that could be causing this? Brakes still seem fine. Good stopping power and pedal travel good, not soft or pumpable.
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post #5 of 7 (permalink) Old Sep 27th, 14, 11:13 AM
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Re: Brake warning light on...dim

Quote:
Originally Posted by trland View Post
Is it something in the ignition switch that could be causing this? Brakes still seem fine. Good stopping power and pedal travel good, not soft or pumpable.
I don't think so to my knowledge unless there is a feedback loop happening. I'm thinking the switch is failing and when its colder you are getting lower pressure reading and the light lights up and maybe as the car warms the switch starts working better. I'm not sure if they can be rebuilt, I've only replaced them in my 72 Impala.

But you should also consider that it is working well and you have a pressure leak somewhere in the system so a full visual and feel for weeping fluid might be in order just to make sure, or just replace the switch but if the new one lights up you have a MC or other system leak.


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post #6 of 7 (permalink) Old Sep 27th, 14, 11:50 AM Thread Starter
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Re: Brake warning light on...dim

Quote:
Originally Posted by 69-Pace View Post
But you should also consider that it is working well and you have a pressure leak somewhere in the system so a full visual and feel for weeping fluid might be in order just to make sure, or just replace the switch but if the new one lights up you have a MC or other system leak.
OK, thanks. I'll inspect the whole system. I can understand how a cold brake system with a tiny leak could develop a difference in front and rear. Maybe when I hit the brakes a few times the pressure equalizes again temporarily. I'm still not understanding how that switch could act like a rheostat with different brightness. I thought it was more of a 2 way toggle switch (only off when it's centered but fully on if it's left or right). Is it more like a dimmer switch?
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post #7 of 7 (permalink) Old Sep 27th, 14, 01:00 PM
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Re: Brake warning light on...dim

Normally it doesn't it pops on once the threshold of low pressure is hit. But when mine was bad I was just eliminating the possibility - I was 18 and what did I know. A 2 dollar switch was cheaper than the brake inspection. Luckily I'm older and wiser and I don't take chances with the brakes. I had the brakes fail - pedal to the floor fail - in my first new car I ever bought. It was a Pontiac so don't kill me.


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