Author Topic: SURPRISE! nothing inside. Where's my brake sensor? (Read 3017 times)

Choking Hazard · « **on:** February 01, 2008, 09:25:14 PM »

I haven't posted in awhile- because I've been driving driving driving! Only 600 miles last week, but 1050 the week before and 1100 the week before that. I just love driving that E30.
I have had a few surprises- the starter jumped out (only held in by one bolt that snapped) in my driveway between trips. And the brake pad wear light has come on. Today I was gonna do the front pads. I can't find the wear sensor at all on the right hand side. No sensor, no clip, no wire at all. On the drivers side the wires for the ABS sensor and the pad wear sensor both exit the wheelwell through the same hole, then are wound into the wiring harness running along the top of the left fender. On the right side, I got nothing. I guess the wire, when there was one, went into the wires that aren't harnesssed together but run to the WW fluid pump and the AC compreesor and the airbag sensor and radiator aux fan power/ temp switch wires. Its gotta go somewhere over there. I'll have to get the wire itself somewhere too. I just received the new pads and wear sensors I ordered from Pelican Parts. The new pads will go back in the box awhile b/c the old pads are only half gone, but that dashlight will make me crazy. Any help out there?

D. Clay · « **Reply #1 on:** February 01, 2008, 09:45:06 PM »

Sensors are on left front and right rear only. The warning light comes on when the sensor is interrupted by a ground.

Choking Hazard · « **Reply #2 on:** February 01, 2008, 10:19:45 PM »

Quote from: D. Clay;42086

Sensors are on left front and right rear only. The warning light comes on when the sensor is interrupted by a ground.

No shit? I'll be dogged. i guess thats good news.

Many gracias.

Choking Hazard · « **Reply #3 on:** February 02, 2008, 08:26:36 PM »

I'm trying to get ready for another trip- only 750 miles or so. I had plenty of pad, front and rear. Now I gotta figure out why the light is on...
Of course, the thing wasn't lit when I took it somewhere to do the starter (I know, its real easy, but I wasn't able to take the time) and I didn't say anything to the guy b/c I had to hit the road the next morning and couldn't leave it.

The light glows pretty dimly, not at the intensity of the others.
Could it be another dash related misbehavior, like the temp gauge?
I don't see anything yanked loose or abraded around the starter, and the wire seems sound all the way to the connector. Does the wire on the master cylinder effect this bulb? I don't think it would....

I don't really like the "Black tape" fix.

I'm perplexed and bewildered.

D. Clay · « **Reply #4 on:** February 03, 2008, 01:26:48 AM »

I use one of the pointed screwdrivers with a bulb in the handle and a wire with an alligator clip on it. Disconnect the plug at the wheel and use circuit tester to connect each socket of the plug. This makes a connection that bypasses the sensor on the brake pads. If one of them makes the light go out you've found it.

twinpop171 · « **Reply #5 on:** February 03, 2008, 05:48:17 AM »

I had the same problem with the sensor light coming on. It ended up being caused by the sensor wires havlng the insulation rubbed of by the inside of the front wheel. Sorry to say but I did the black tape fix on that one.
BTW, hit the road again.

Dan.

Choking Hazard · « **Reply #6 on:** February 03, 2008, 10:58:26 AM »

Quote from: D. Clay;42125

I use one of the pointed screwdrivers with a bulb in the handle and a wire with an alligator clip on it. Disconnect the plug at the wheel and use circuit tester to connect each socket of the plug. This makes a connection that bypasses the sensor on the brake pads. If one of them makes the light go out you've found it.

Quote from: twinpop171;42130

I had the same problem with the sensor light coming on. It ended up being caused by the sensor wires havlng the insulation rubbed of by the inside of the front wheel. Sorry to say but I did the black tape fix on that one.
BTW, hit the road again.
Dan.

Circuit test idea is great (duh), I'll do that and see if I can isolate it. I was thinking the new wear sensor (which is just a loop of wire in a little plastic sandwich) would either work or it wouldn't. Maybe I do have poor connection at the plug I can test with a jumper....
Dan-
I may end up in cover up mode until next weekend if these basic approaches don't work
:cool:

sheepdog · « **Reply #7 on:** February 03, 2008, 01:19:36 PM »

I just bypassed mine.

Not really necessary, you will know when your pads are toast.
I will be needing rotors when I do pads next time anyhow. Not that i expect it anytime soon.

Choking Hazard · « **Reply #8 on:** February 03, 2008, 03:23:38 PM »

Thats the route I took, and I could tell it wasn't gonna fix the problem. When I disconnected the sensors the light glowed brightly. So now they are bypassed and the light still glows dimly. I'm convinced it is related to the starter replacement. I'm thinking it is grounding through the starter motor or the solenoid or something. Somebody pleae review the starter wiring for/at me. I think this starter that was put in is not stock but one of those e-bay gear reduction starters from china. I see the thick cable coming from the battery going to the large post on the solenoid, and two others going to smaller posts (two different sizes) on each side of the solenoid. One's gotta be the ignition, and the other probably is the alternator, but I could be wrong. Question is- where are these supposed to go? I don't want to fry the alternator. Are they supposed to be on the same post? Will it damage the alternator to disconnect it then turn the key? I'm pretty sure on my 914 that the ignition and alternator both are attached on a single post. Somebody smarter than me (well OK, that doesn't impact the field much- I'm not so bright, it should be "Somebody experienced") will need to hep me through this I'm afraid.