Touchy W123 Voltage Regulator - 3 Warning Lights on at Same Time

[pwjeep]

The fuel resevoir, brake AND pad wear indicator are all on at the same time. When I press down the parking brake the brake warning light gets brighter. (when I release the parking brake the light gets dimmer) By the way, the master cylinder was full, the brakes were fine and the fuel was at 3/4+.

The first time this happened after I zapped the battery with an electric spark arc with a crummy battery disconnect (green thumb screw which I dumped) unit. This happened when the connection was not tight and the engine was running. My fix then was to replace the alternator voltage regulator with a new one. It seemed to work fine (no warning lights lit) until got out the jumper cables and I jumped another battery with the car running. Yup, I zapped the battery with another electric spark (doh!). No, I didn't put the negative jumper cable on the engine to ground it and the positive cable on the positive terminal.

I then got a used regulator from a friend and changed the regulator again, hoped that this solved the problem. However, beware of good looking voltage regulators from unknown sources. (unknown condition of used unit). I thought I was on the right track, but I still had the same 3 warning light issue.

I again bought a new voltage regulator and installed it. TA DA!!! the problem is solved.

So the lessons learned are: (1) don't jump another car with battery cables hooked up directly to the battery when your car is running. (2) hook one jumper cable to the engine block or some other ground. (3) don't trust used electronic stuff unless you know for sure that it was working when it came out of the donor. (4) the diodes in the voltage regulator are really touchy and don't survive electrical shocks, (5) don't use the cheesy battery shut off unit with the thumb screw.

My replacement time has improved from a sweaty 2 hours to about 30 minutes. So I guess I got better.