528i Brake Sensor Light (1997)

[vparsegh]

My red "Brake" light on the dash came on. Since I knew the rear pads were thin (from an inspection before I bought the car) I assumed they triggered the sensor, I replaced the pads and sensor. The light stayed on. It did not appear that the old sensor had worn down to the metal probes that would have caused the light to go on. The brake fluid reservoir is full.

Thinking it may be the front pads which I had not previously inspected but found they were pretty worn also, I replaced them and the sensor. That sensor also had some worn plastic but not down to the metal probes.

My assumption was that the 2 pad sensors or the fluid level float are what could trigger the "Brake" light on the dash. Using an Ohm meter to test the sensors, I concluded that a "short" as opposed to an open circuit would trigger each of the 3 sensors. So that unplugging them as a test should eliminate the possiblity of them triggering the light.

1) Are there any sensors I am overlooking?

2) Has anyone confirmed that if a sensor is triggered unplugging it will turn the light off?

3) Does the light need to be reset in the computer or should it go out once the sensor if fixed/unplugged?

Otherwise, I am agraid that if there are no other sensors and unplugging should turn it off that there is a short somewhere in the system.

Thanks for any help on this. Hate to pay to get this fixed since it appears that the brakes are working fine and the only problem is that the light is on.

[venzon]

1) There are no other sensors that I know.

2) If you unplug the sensor, it will turn the light on.

3) The light does not need to be reset.

Are you sure you are looking at the "brake lining" not the "brake light" warning lamp? Make sure the sensor plugged connections are clean and tight. Try bypassing the sensors one at a time by unplugging and short circuiting the plug using a short wire or even a paper clip. Also, I believe air in the system or low fluid will turn on the light. Good luck.

[BAVARIANM]

if it's actually the brake lining light, and the reservoir ius full, Try turning the key to the run position and engine not running for 30 seconds

[vparsegh]

venzon,

Thank you for your reply. I did read about the "brake lining" light but I looked in my manuel and my dash and it appeared that instead of that I just have a red light that says: "BRAKE". It is not for the parking brake as there is a red one next to that: "PARK BRAKE" which works fine. It is a 1997. There in not one that says: "BRAKE LINING" and I accounted for all the other symbols.

Good point about the possiblilty of air or water. If that is the case there must be a sensor somewhere to detect it. The only way I can think of to do that would be to check the fluid pressure when the brakes are fully applied. Would have to sync with the time when the anti-lock is triggered. If the pressure was low, then there could be water or air in the lines.

I will try shorting the 3 sensors again. If I don't have a seperate brake lining light then maybe the new sensor for the rear lining I bought from the dealer is defective.

[vparsegh]

Thanks Bavariamn,

I just tried that and it did not work. I will try that again each time after I replace and/or short what may be a defective sensor.