1982 911SC won't start, no 12V to the coil.

[Bobbo911_79]

I get no spark from coil (MSD type). I get no 12 V at the coil. I had the motor apart to change the tensioners and the right cam sprocket. I had the distributor out, but I think it's back in the correct place. I found some exposed points in the green wire to the distributor. I taped those, and checked the wires with a DMM to be sure they went to the CDI unit. I swapped CDI units with the one from my '79 (same part number). What should I do next?

Thanks,

Bob

[Bobbo911_79]

OK I've read the early CDI troubleshooting guide, and I will set up a test bench. I don't recall hearing the CDI whine lately, so I'll start by cleaning the grounds and the fuse connections. I'll probably replace the green trigger wire to the distributor because it was nicked and I want to rule it out.
My only question now is if the later CDI units can be tested in the same manner as the early ones described by Early_S_Man in the "History of Bosch CDI" thread.

Thanks,

Bob

[Early_S_Man]

Bob,

Here is the equivalent thread to the 'History' thread for the SC 6-pin CDI units:

6-pin SC/Turbo CDI unit repair documentation

Here is a recent thread where I gave the gamut of troubleshooting tips for the 6-pin units;

Engine shuts down

[fastfredracing]

I had done some work that disturbed the distributor wires, and same problem, the trigger wires that attach were brittle, and were broken back a couple of inches back from the dist, hidden inside the wire covering,
Good luck

[Bobbo911_79]

Warren,

thanks for the links. The CDI unit is squealing, but it seems a little quiet. I measured the voltage at 11.5V so I charged the battery.

I measured the magnetic pickup at 600 ohms. I changed out the green trigger wire (two bare spots but it measured ok from the CDI plug to the contacts).

I cleaned up the grounds at the battery, the chassis and transmission, and the plate in the engine compartment. I measured .5 ohms at all the grounds.

I measured 1.0 ohm at the primary coil windings and 4.5k at the secondary, so I changed the coil.

The good news is it started up! I just don't know exactly what was the problem.

Thanks for your help.

Bob Morgan

[acapella8]

EarlySMan, your posts are a tremendous help to those who are new, and to experienced alike -- thank you for sharing your knowledge. Your help with my GREEN wire hell and AAV were invaluable.

-Tom