bd0nalds0n

I have been getting the brake pad warning light over the last several days. It comes on at different times (between immediately and 30 minutes of driving). I pulled off all four wheels expecting to find a bad sensor/worn pads. Pads are still in great shape and the sensors are all intact.

I suspect an intermittant connection, which I didn't pay much attention to as I did each wheel, since I was expecting to find a bad sensor somewhere.

So I'll pull all the wheels again and check the sensor plugs.

If all the connections are tight/clean, I think the next step would be test each of the sensors for continuity.

Is there anything else in the system that could trigger the brake pad warning light other than loss of continuity from one of the sensors?

Gretch

Low brake fluid in the res.............or is that another sensor......

the flyin' scotsman

Brian..............the circuit is grounded when the sensors wear enough.

Test the sensor wiring for continuity to ground. Once you find the bad circuit/wire you'll have to trace it to where its shorted to ground. Rather than use a DVM you could use a test light hooked to the +ve 12v source............that way when you find ground the light shall illuminate.

Nicole

I had the same problem, even though the rear sensors were relatively new. So we replaced the front pads and sensors - with no success. Then we replaced the rear sensors, and that fixed the problem. There was no visible damage to the old sensors - we were not able to tell why it triggered the warning.

bd0nalds0n

Sorry to sound like such an electrical oaf, but here's what I hear you saying:

I should unplug each sensor (but leave it attached to the brake pad), hook up my test light to a +12V source, and stick the test-light point in each side of the plug, and when it lights up I have found the sensor that is grounded?

If the sensors ground when they fail, why 2 connectors on the plug? Wouldn't one suffice?

I (apparently mistakenly) thought that failure caused a circuit to be broken. I guess the system wants to know if a) all the sensors are plugged in (creating an unbroken circuit) and b) will give a warning if either of the two wires on the plug becomes grounded.

Am I even close?

Gretch

One for each pad.....sometimes a piston can get stuck, since the calipers don't move (as they do in a single piston set up) the pad on the stuck piston would wear much more rapidly than the pad on the other side of the caliper.

j.kenzie@sbcglobal.net

I thought the brake sensor was an encased wire loop that was interupted by abrasion upon continued contact with rotor. This is the basis for the questionable practice of jumping the contact to remove warning light and also why the sensor can't easily be reused once activated. Mine is an 84, maybe it's different on other MY's.
Anyway the sensor would produce an open condition and warning light if abraded through or if not properly connected all the way to the sensor brain.
Dave McK.

ew928

The sensor that I pulled out of the 88 S4 was a wire loop.
When wire breaks, triggers brake pad warning.
Found a bad front sensor. I just built an electrical bridge (shorted the wire)
at the plug and cut off the sensor.
One more thing to replace on the shark.

Use DVM. Use resistance testing mode and find out which sensor has
no continuity. (Infinite resistance)

Ernest (NYC) A few warning lights. Some duct tape. Few zip ties. Still running.

Paul D

The sensors will activate the warning light when there is an 'open' in the brake pad sensor circuit. The brake pad sensor is simply a piece of wire that connects 2 wires together. One way to test for a working brake pad sensor is to disconnect the pad sensor leads from the wiring and place an Ohm-meter across the leads of the sensor. It should read very close to 0 Ohms. Wiggle the sensor/wire and verify there is not an intermittent open in the sensor. There could be an intermittent at the sensor connector or further back in the wiring as well. Good Luck!

Gregg K

I had the same problem. There's a post on it in the archives.

All the sensors ohmed out good. But by pulling one at a time, I found the one that was bad. It went something like that. I think I actually pulled one at a time, and shorted out the harness. And when the idiot light didn't light, I knew I had the bad sensor.