Robert Coats

I understand when the brake pads wear to a certain point, the indicator light comes on, but could somebody explain exactly how it all works?

On my car, (’91 C4) the indicator light came on about a month ago, but then would stay off for a while, the pop back on. I finally got around to inspect the pads for wear yesterday, and pulled off the left rear wheel.

Well, well. What’s this?

The short length of two red wires that connect the inboard pad to the outboard pad had come loose from it’s little clip, and a good chunk of the insulation had worn off, clearly from rubbing on the inside of the wheel. Ah-ha, thought I, there's the reason why the indicator has been on-off-on-off for the last month. Let's see, yep, the pads look okay, about 50% gone.

I cleaned it up, taped up the wires individually, then tucked them back into the clip.

Started up the car, and oops, the indicator light didn’t go out.

Now what?

What causes the indicator lamp to go on?

Must it be reset with the “hammer” or should it go out when new pads are installed?

Tell me how the circuit works on the brake pads. Specifically, if the two wires from the outboard pad are damaged, broken, etc., how does that (possibly) make the indicator lamp go on?

Thanks

SteveW@stig

The warning light on the dash will come on if the sensor circuit is shorted to ground or goes open circuit - fail safe.

Taj

So, if the pads are all ok, and the the discs are not worn to the point where the lip on the outer edge is rubbing on the wear sensor, then I would guess that all you need to do is replace the one damaged sensor and all should be fine. You could also check your damaged sensor with an ohmeter to see if has an open circuit.

Taj.