Hi Guys,

I'm looking at a pretty nice 1991 560SEL. Everything seems to work well except for one issue....the owner says that when the original Becker is on, sometimes it shuts down the entire electrical system and the car goes off. As a result, he has driven the car without the radio on for years, but doesn't want to replace it with an aftermarket because he doesn't want to change the original configurations in his beautiful car.

He insists this is an electrical fault. But it sounds to me more like a security code bug or something like that.

I've searched on this forum to try and find the answers, but so far no luck. Anybody have any ideas?

That does sound like an electrical fault. The becker in that car has 4 pieces... the headunit, tuner in the trunk and 2 amps behind the rear seats. If any of those short it will blow the fuse, which also runs the dome lights and the clock.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

I would ask him specifically what happens.

Does the car stall? Does not stall with the radio off?

Does a fuse blow? Or no fuses blow?

And what all else is turned on when this happens? Headlights? Rear window defrost? Other heavy users of electricity?

Does this happen when stopped at a traffic signal / stop sign? (Engine/alternator running slow.)

I would install a voltmeter and see what is going on. It could be with all the other electrical loads on, the radio is the "straw" which along with a weak alternator or voltage regulator causes the car's voltage to drop too low.

There could also be a poor electrical connection and not enough power is able to get through to the inside of the vehicle. And only a limited number of electrical things could be on at the same time. (Measure voltage at battery as well as inside the car - may be drastically different!)

Or it could be that a power wire going to one of the radio components is brushing up against a sharp metal object and grounding out. Maybe just when going over bumps in the road. If that is the case, it should blow a fuse.