Quote:
Originally Posted by zeke
I am so afraid of that! 
OK, so I didn't have to start the car at all - I realized that the brake sensor is activated in the last accessory position of the ign switch.
In the 240D, the yellow light comes on before ignition.
In this car the Alt light used to come on prefire, then stay on after ignition until I hit the throttle the first time. Can't remember the last time I saw the yellow brake light.
Now neither light comes on.
So I tested the voltage across the sensor wire leads and with ign off, it is 0, with ign in last position it is ~12 (GP relay was active in that position too, so it droppped duing that).
Then I tested current from the hot lead of the brake wire plug on the PS (melted one) to the neg. terminal of the battery.
No continuity down to 200k range, and there it read ~163 ohm
Moved to the DS for comparison: No continuity down to the 200 (smallest) scale, but there it pegged and the meter screamed at me. Back up, and it shows no continuity at larger scale???
Not sure how to interpret this. |
I'm not sure what you're saying/measuring here. If you put an ammeter to measure current from the hot lead (+12v) to the neg side of the battery, it should have sparked, then blown the fuse since that would be a dead short from +12 to ground. Unless by "hot" you mean temperature 'hot' (melted) and not voltage 'hot' (+12v) and you're looking for resistance/impedance (ohms) and not current (amps).
Can you tell what color wire you're measuring: brown or brown/red? If brown, then you should have very low ohms from that pin to ground. If brown/red it could give some funky readings since the meter may get confused by the added current from the car in addition to what it's providing.
Does your parking brake light work? What about the low fuel light? These lights share a connection on the cluster wiring trace that goes back to the alternator. It's possible a short in the cluster or at the brakes may be contributing to killing the regulators in the alternators.
Can you set your meter to Amps (current) and then connect from the brown/red wire on the "car" side of the sensor to ground and measure what happens with the ignition on? You should see a low current draw that equates to the light bulb in the dash and see the bulb glow. You're basically replicating the pad wear sensor closing. Assuming something like a 1.2 Watt bulb, the current ought to be 0.1 Amp (P= IV, 1.2 W = 0.1 A * 12 V)