Odd alternator behavior

[pryantcc]

Hi guys, I hope someone can help me.
I've installed an alternator from a 1999 Mercedes e300 diesel into a 1971 280SE. I have removed the regulator from the original setup as it's built into the new alternator. There are only 2 terminals on the back of the new alternator. I have connected the indicator lamp (small terminal) connection into the corresponding cable on the 280SE harness. The large terminal is connected directly to the battery. When I turn on the ignition, the alternator light on the dash comes on. When I start the car it goes off and the alternator is delivering charge. Up to now, everything is normal.

Problem arises when I switch off the ignition. The engine stays running and I read approximately +5V on the circuits which switch on with the ignition (wipers, lights, indicators, ECU etc.) and the alternator light is dimly illuminated (presumably because there's ~5V across it. It seems like the 5V is enough to keep the fuel solenoid open which is why the engine doesn't shut off.

If I disconnect the small terminal on the alternator, everything works exactly as it should (except the light on the dash, obviously, which remains dark).

I should add that it's a diesel engine.

Any ideas?
Thanks,
Paul.

[suffolkpete]

One of the diodes feeding the warning lamps is short-circuit.

[pryantcc]

One of the diodes feeding the warning lamps is short-circuit.

Is that in the back of the alternator Pete? Something replaceable?

[suffolkpete]

Should be replaceable, I'm not familiar with such top-end machinery