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I have an W220, CDI320, year 2002, 12 month. When I start the car the alternator only starts to give power when it reach 1500 Rpm. After this all is normal.
I have done these things:
Replaced alternator to a new Bosch
Replaced the motor heater Replaced the SAM right side front
Measured the wires in this orbit - (blue one goes from SAM to alternator, blue/white goes from alternator to motor heater, blue/purple goes from motor heater to ECU. All wires is okay.
Extra info: I have an active fault code "motor heater signal wire open circuit" and I do not have any other active faul codes.
I have no info on the excitation circuit on the W220 - but in other cars, your problem is often a problem in the alternator excitation circuit. An alternator needs voltage (excitation) to create the field circuit to start generation at low RPM. If there is no excitation voltage, the alternator has be be spun to a high RPM so that the small amount of residual magnetism can kikc things off.
I have no info on the excitation circuit on the W220 - but in other cars, your problem is often a problem in the alternator excitation circuit. An alternator needs voltage (excitation) to create the field circuit to start generation at low RPM. If there is no excitation voltage, the alternator has be be spun to a high RPM so that the small amount of residual magnetism can kikc things off.
Thank you very much. Will it be possible to give the alternator start power maybe on the blue wire from SAM to alternator?
Please see the measurement: when the ignition is connected I have 11.74 volts on the battery, but I have 10.27 volts on the blue wire to start the generator?
11.7v on your battery? That's a nearly dead battery. Totally discharged. Should be closer to 12.7 for a fully charged AGM at normal temperature. Makes me wonder if you've got a battery problem that's causing the alternator problem.
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