Pesky red Brake light

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AV8R4AA
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Joined: Sun Oct 02, 2016 3:48 am

Pesky red Brake light

Post by AV8R4AA »

If I know the system well enough, I have 3 possibilities.
Low on brake fluid, one of the 2 pressure switches might trigger the light.
I have no leaks, the power steering works perfectly, brake fluid level full.

Brand new brake bomb installed 2 months ago.

What might I try next?

1986 635 auto transmission.
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sansouci
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Re: Pesky red Brake light

Post by sansouci »

I had my brake pad sensor wire get chafed so it periodically grounded. Found the bad area and taped it up. That could be your problem.
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)
maj75
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Joined: Fri Mar 24, 2017 3:27 am
Location: Florida

Re: Pesky red Brake light

Post by maj75 »

My 633 had the brake light on when I bought it. I topped up the fluid, rebuilt the SI Board and the light was still on. Replaced the pressure sensor (which was leaking) on the top of the accumulator, light still on. Replaced the one on the side and the light is now off. My brakes always felt fine so I didn't think it was a bad accumulator.
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MVX11V
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Location: East Anglia, UK

Re: Pesky red Brake light

Post by MVX11V »

I have just been through 2 months with the light coming on and going off, over bumps. I had a brass header tank in there which was leaking at the seam for months. It was dripping onto the ABS block below. It got worse.
I replaced the tank with an new one and almost immediately the brake light stayed off. Fixed two birds with one stone. Only another 297 issues to fix!
'HAUNTED :evil: ' and playworn 1986 635 Daily.
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Brucey
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Re: Pesky red Brake light

Post by Brucey »

there are several brake warning lights; they all do different things, so the one that senses brake pad wear cannot come on if there is a hydraulic fault, for example. So it is important to be sure you know which light is coming on, else you can spend time chasing down a fault that doesn't exist....

Off the top of my head there are separate lights for

- handbrake action
- brake pad wear (light comes on if circuit broken)
- brake fluid level warning (light comes on if circuit broken)
- ABS system (can indicate various fault conditions)
- hydraulic system pressure ( can be high or low)

if I ever see one of these lights I usually have to check in the owner's manual to remind myself of which one it actually is; this can save an awful lot of time..... :wink:

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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sansouci
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Re: Pesky red Brake light

Post by sansouci »

I may have spoken too soon. I am getting that recurrent brake light indicator and a hard pedal. I wonder if my rebuilt MC is not releasing properly. I know the booster is in good shape as I had Jay Stratton rebuild it at the same time as I put in the M/C. Time to get under the car to take a look.
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)
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