Questions and Answers

Mercedes Benz 300SD No-Crank Q. Hello, I have a 1983 Mercedes Benz 300SD turbo. My problem is the last time I turned it off it will not start. I have tried to jump start and checked the battery I have dashboard lights when the ignition is turned on but when I turn the ignition to crank it does not do anything. Anything about possible causes would be greatly appreciated. Thank you, Robert

A. If I'm understanding you correctly, you have a no-crank situation. If that is correct, it will be fairly easy to find the problem.

I always start at the starter end of the circuit since I find it is most often a starter motor that has gone bad. Using the wiring diagram, check for power at the starter motor. If you have power there with the key in the START position, you do indeed have a bad starter motor.

If you do not have power there, you will need to trace the circuit back towards the ignition switch.

Connector C105 is under the hod towards the rear of the engine compartment.

You did check all the fuses first, didn't you? Those fuses weren't the greatest ever made and I have seen, many times, where they break a filament or contacts and cause all kinds of outages.