Red warning light - 230 SL

[coupegt]

Hello.

I have recently been so lucky to get my self a 280 SL from 1966.
The car was originally a 230SL - but someone decided to drop a 280 engine into it.

I only had it for a couple of months now - and unfortunately no owners manual availble.

Last time i drove the car a red warning light came on - I have been reading but it seems it can "door ajar" - "low brake fluid level" or "alternator not charging"

As my car is euro spec. originally (though exported to US and back again) I do not think I have a brake fluid float - I do not see any float in the brake fluid resovoir anyways and no electrical wires.

The light is brigth red when not idling - and goes a little dim when engine is idling - if it were low voltage would suspect the light to behave opposite?

The oil pressure indicator goes to 3 bars when engine running so oil pressure seems to be ok.

So what am I dealing with here?
Bad alternator - low oil pressure, faulty door switch or what?

Thanks in advance

[Jonny B]

It would seem unlikely to me that the red light is for the door ajar or brake fluid, if the car is indeed a 230 SL with an update motor. Especially since you cannot see the sensors for the brake fluid. The later cars had a brake fluid reservoir with two caps and the associated sensor is mounted just below each cap.

Have you had any trouble starting the car, that is, anything that would indicate low voltage on the battery. It would be good to check the battery when the car is off, and when the car is running to see what differences, if any you see on voltage.

With the change in engine, could the wires for charging light have been switched around?? I am traveling today, and don't remember off the top which of the lights is which, that is, top one charge, or middle one charge??

[w113dude]

most likely bad regulator.

[georgem]

Hi coupegt,

I`m with the dude - probably two options - the alternator diodes are toast (repair or exchange alternator) or the regulator (small box on the wheel well wall  just back from the air cleaner) is knackered - an auto electrician will tell you in two seconds with a tester which one it is.