Mercedes-Benz W639 will not start although the power comes on
W639 will not start although the key works and the power comes on - what is the fault?
The cause may be the ignition switch, the steering lock, the fuse holder or the starter motor. The diagnostic tool may show the start permissions as fine even though the starter relay gets no signal. In that case the fault may be in the ignition switch.
The key will not turn and there is no power although central locking works - what is the cause?
The steering lock may be seized. Then the lock does not release and the power is not switched on. Turning or tapping the steering wheel does not help. Replace the faulty part. The steering lock is tied to the immobiliser and the steering, so replacing it is a job for a workshop.
The power cuts out when trying to start and the voltage collapses under load - what should be checked?
Check the 80 A fuse holder under the driver's seat. It may have a contact fault or broken wires. The voltages can look fine without load but collapse under load. The fault was fixed with a new fuse holder.
The starter solenoid clicks but the engine does not turn - what does it mean?
The click points to a fault in the starter or its electrical supply. The diagnostic tool does not show a starter fault directly. If the starter is faulty, it is replaced with a new one.