What happened to my car?

[rammstein]

I go to park, put the parking brake on, and I notice that in addition to the parking brake light, the "Brake" light and "Battery" light both come on slightly. I pull the brake on and off a few times, but it stays that way. I get out and a few minutes later return and start the car once again and the lights are still on. I attempt to fix the problem by hitting the car, which used to work in my old 944 suprisingly often. No, the E30 does not respond to hitting. So anyhow, I begin to drive home. I notice that now that it is dark out, my dash is not lighting up particularly bright. Then the ABS light come full on, and a few minutes later, the check engine light comes on. Now mind you, the car is running fine during all of this. I also note at this time that the headlights are not really lighting up all too much. I try the high beams. THAT produces a response from the engine, meaning that at idle, with the highbeams on it just about stalls. I turn off the headlights, and the idle resumes. I roll up my window, and whlie rolling the engine stumbles again. This makes my primitive mind think that I either have a battery or alternator issue, but I am just suprised by all the weirdo warning lights. Anyone have advice on how to proceed? Do I just throw a battery at it and see if it likes that?

[kronus]

It's either an alternator or a cluster issue. Get a friend (or a brick) to give it some gas and measure the voltage across the battery. It should be north of 14V if it's charging properly.

If not, your battery may have dropped a plate and is shorting through itself (bad), or your alternator is no longer charging the battery, which could be caused by several things. If you have an early model cluster, there is a light inline with the battery charging circuit that can blow and render the whole chargin system inoperable (which is a shit design, yes). If not an early model, your alternator's charge diode may have exploded, or the alternator itself could have bucked the kicket. Poke at the Bentley, it should have several pages dedicated to troubleshooting this.

[rammstein]

It is a late model cluster. I have a bentley for E30s, but seeing as how the alternator is going to be for the M52 engine, I'd better get searching for a bentley on that. In the meantime, I'll test the voltage at the battery while the car is running. Assuming it starts in the morning. The bad alternator/regulator theory seems likely, but that would suck because they seem like they are $300 or so as I search.

[funcrew]

I'm an old geezer. In many many years of having weird electrical problems in POS old cars, replacing the old POS battery with a brand new one has fixed 80% of the problems in 80% of cases. Your mileage may vary. I've never had a bad alternator in all that time.

[rammstein]

Followup- interestingly, at first a new battery got it done, but then once the car warmed, it died again- the alternator was toast, but only became nonfunctional once warmed. Since its replacement, I've put about 10 hours of driving in and its all good now.

Thanks!

[funcrew]

Good to know. Thanks for the followup.