something kind of weird
 

Last night while my 90 300 SEL was sitting idle with AC on, the SRS and the ABS lights came on and the AC started to "kick" in and out. I started to drive and the SRS light went out but the ABS light stayed on and the AC still would speed up and slow down. The fan I mean. I shut it off for a few minutes and it seemed to have cleared up after that. Any idea what that may have been about?

you mean like the fan?

reason I ask is that my 1990 300TE is goofy son of a gun as well in that regard and I ignore the thing....tempermental piece of technology....the climate control system wants to run everything for you, as if you are idiot or too important to actually do it yourself....I just put it to all warm or all cold and screw the fan control thing....what junk...I swear that is where I draw the line between MB and BMW....MB is so concerned about you, the driver, not having to do anything other than the pleasure of motoring that they overdo this kind of crap....BMW concentrates more on the actual automobile fundamentals..handling, engine....tell you what...I gotta go with BMW over Mercedes as far as quality....I hate to say it but I must

Yes the fan. It was cutting in and out, speeding up and slowing down in sync with the ABS light. Not sure how ABS is tied with climate control but... anyways I have never owned a BMW

From your description it sounds like you may have had a low voltage condition.

Agreed...have the alternator checked by a trusted tech...ABS or SRS light coming on for unrelated problems is a symptom.

Also check condition of battery terminal connections, esp. the ground; modern electronics get goofy fast when the electricals are not good. Maybe the battery needs to be replaced?

I never thought of that but it probably does. I know the charging system is fine.

You KNOW that the charging system is FINE? It sure doesn't sound like it. Even if it is, you have a power supply related problem and on an automobile the power supply is the battery and charging system.

Check your battery cable connections. Make sure they are clean and tight. Then using a simple Digital Voltmeter check the voltage across the battery with the engine running. If it is less than about 13.5 Volts then you do have a charging system problem.

Good luck,

Exactly how, without checking it?

When multiple things happen, the system voltage is one of the first things to verify.

Jim

Wont a bad OVP relay cause the ABS light to go on and off?
Mick

Did the idle speed vary as well? My first guess would be the OVP relay.

idle stayed the same.