I changed the dist cap, rotor, points and condenser on my 1972 6 cyl 250C. Now I have no voltage to the ballast resister or the input to the coil. The engine turns over fine and everything else on the car works. The ign switch seems ok. I traced the wires from the ballast resistor to a large electronic module (?) located below and to the front of the battery box. What is this unit? Could this be my problem? How do I trouble shoot this unit? Thanks!!!!! Dave.

Was it working before you started?

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

This was one of the 1st attempts at an electronic ignition system. The ECU "was" a high fail part. Most of the later boxes seem to last a long time. The points are the weakest part of the system now!! The current flow across the points is so low that even the smallest speck of anything will hamper their ability to trigger the ECU. Try to clean the points w/clean white business card.

Benzmac, Yes it was I just pulled it out of storage and had been driving it about two weeks.

MB Doc, thanks for the info and the tip. It led me to investigate futher and found the root problem, a corroded terminal under the battery box where the wires from the Unit, the dist and the coil come together. Also even though the points were MB and brand new I cleaned then with Acetone and then a dry business card. They were very dirty even new. Always pays to check the small stuff. Thanks Dave..........