No Speedo, ABS & Brake warning lights stay on

[HF2]

My ABS and brake warning lighs are constantly on, and also the parking brake light does not illuminate when the parking brake is applied.

Reading through the various threads where similar issues have been discussed the problem could be either the parking brake switch, brake pedal switch, OVP relay or even the ABS sensors.

Before I start pulling things apart I have a couple of questions:

1. If the brake pedal switch was faulty will the brake lights still light up when the brake pedal is depressed ?

2. Would a faulty parking brake switch cause the ABS not to work or are they separate issues ?

3. What's the best way to test the OVP relay ?

I have fitted new front pads as the old set were worn down to the metal (I blame the previous owner !). I have also fitted new rear disc's and pads as well as shoes expecting the warning lights to clear but no joy

 

[bedwards1966]

1. Probably not, but it might depend on how the switch fails.

2. I can't see that it would be related

3. Not sure.

I'll have a go at answering this as nobody else has yet, what model car is it?

Firstly, I'd check each fuse on the car.
Then I'd be thinking of an ABS sensor (I'm thinking it'll be a front one that will work the speedo). They can be tested by using a multimeter to measure the resistance of each sensor one at a time by unplugging each sensor from the ABS ECU, and seeing which one gives an odd reading.

As to the parking brake light, I'd be testing the switch to see if that's the culprit. If it's working OK, then perhaps it would be the bulb in the dash.

 

[HF2]

1. Probably not, but it might depend on how the switch fails.

2. I can't see that it would be related

3. Not sure.

I'll have a go at answering this as nobody else has yet, what model car is it?

Firstly, I'd check each fuse on the car.
Then I'd be thinking of an ABS sensor (I'm thinking it'll be a front one that will work the speedo). They can be tested by using a multimeter to measure the resistance of each sensor one at a time by unplugging each sensor from the ABS ECU, and seeing which one gives an odd reading.

As to the parking brake light, I'd be testing the switch to see if that's the culprit. If it's working OK, then perhaps it would be the bulb in the dash.

Thanks.

In the end it was due to faulty relay (£74 from MB). I opened up the old one and found one of the relay's had burn marks and also the resistor close was loose.

The parking brake light issue turned out to be due to a blown bulb in the dash.

I'm a happy bunny :bannana: !