New to E30's

[jairoxmalagon]

Picked up a 1991 318is earlier this week and I have been trying to familiarize myself with the car but I can't for the life of me figure out what this is that's hanging there by the rear right tire. Any help? Where does this belong? I have a tachometer and fuel gauge that have been bouncing around. Could they be related?


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[Cosmic Serpent]

looks like the harness for the brake pad wear sensor, zip tie it out the way if you cant find the other connection. As for the bouncing gauge that is usually a grounding issue on the back of the cluster.

[jairoxmalagon]

Where would the other connection be? I already tore at the cluster and addressed the grounding issue and it fixed the tach and mpg but now it's my temperature gauge that's acting weird.


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[Cosmic Serpent]

if it is still attached it will be hanging from the brakes, chances are its long gone as I dont see it in the pic. #9
With the temp it should also be a grounding issue if it is just bouncing, recheck the grounds as its easy to miss one.

[jairoxmalagon]

Would not having that sensor operating the way it should affect anything else anywhere else in the car?


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[Cosmic Serpent]

No it should not affect anything else on the car, it is there just to tell you when you pads are bad. You can get a replacement online or just zip tie the harness out the way.

[partner103]

There are two of these on your car. They are diagonal to each other.
1 on the front left wheel (driver side) and the other is on the rear right wheel (passenger side).

As other said this is the brake pad wear sensor, starts flickering or comes on solid when your brakes need attention.
Do you have this symbol on, on your cluster?



If your gauges are bouncing around I can assume the following:
batteries on your SI board may need to be changed
grounding nuts on the fuel and temperature may be loose

The brake sensors, IMHO, are not related to the fuel gauge and tacho jumping

[Cosmic Serpent]

it is my understanding that that light will only be on if the activated by the brakes being used up, not if it is disconnected as in the op.

[partner103]

You are absolutely right, that SHOULD be the case. There can be cases when the light comes on whether the sensor is connected or not.

A friend on mine had this issue. His brake pad light started to flicker, then turned solid. So we decided to change his brake pads. We jacked up the car and the rear sensor wire was not connected. To be fair he did have some wiring exposed.

I have another thread in here where I had brake pad light trouble. My pads are 3 months old, sensors are also good. Yet my light is on.

[Cosmic Serpent]

Interesting, do you think it might be something wrong with your cluster?

[partner103]

Don't want to thread jack this one.
Check the thread just below this. Has all the details. Cluster is fine. May need to change the sensor again.

Have another member who had to change a week later. Faulty sensor.

[long tall eta]

could it be the ABS sensor? where do the wires run to?

[Semblance]

The brake pad light will only be off if you have a sensor connected and it is in good shape. If the sensor (or an wire on the circuit) grounds out, or if the circuit is open (no sensor), the light will come on.

You can try jumping the open end of the sensor harness to see if that turns off your light. If not, you have an open or short somewhere else on the circuit.