No power to spark box!
 

I have a 83 911 that is having intermittent ignition problems. I have narrowed the problem down to power not getting to the CDI box. I have replaced the ignition switch (along with a lot of other parts that were not part of the problem!). Anybody have experience with this? Any suggestions on where to start looking for the shorted wire?
Thanks!

Darren,

This type of problem is the clearest example of the failure of the 'current-flow' diagrams used by the factory since 1974 to convey where in the vehicle parts and wires are located! I will use both the '82 current-flow diagram and the 1973 diagram from Pelican to try to simplifythe troubleshooting.

I can't say I have traced the wiring of an SC relay/CDI/fuse panel, but I have on earlier cars and feel there is close 'family' ties in the history of the 911 to state that few changes in the history of CDI-unit wiring on that panel since 1969.

With the above premise, I refer you to the two 14-pin connectors in the two following diagrams. The first diagram is a 1973 CIS car, and the two 14-pin connectors are located side-by-side to the left of circled identifier #84. The leftmost (forward on the panel) 14-pin connector connects to the body wiring harness. The rightmost (rearward on the panel) 14-pin connector connects to the engine wiring harness. In the lower
'82 SC diagram, there is a connector labeled 'T2a' that corresponds to an unlabeled connector on the red power lead near the #9 CDI-unit in the '73 diagram ... that is a 'pigtail lead' coming off the #2 pin of the forward connector, and goes into the main harness coming directly off the engine from distributor and coil into the three or six-pin connector on the underside of the CDI-unit.

My suggestion at this point is to remove the relay/fuse/CDI panel from the engine compartment and examine the 14-pin connectors, and the power lead pigtail into the harness for the 6-pin connector for the CDI-unit.

http://www.pelicanparts.com/911/911_..._CIS_Part2.jpg

http://www.pelicanparts.com/911/911_...SC_Part1-2.jpg


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Warren Hall
1973 911S Targa
1992 Dodge Dakota 5.2 4X4 parts hauler