Help me out here, we’re running through the wiring on the track project and I’m good with everything on the factory wiring diagrams EXCEPT the section at the very top. Can someone shed some light on what the number designations are that are shown ‘in the fuse panel’ at the top of each schematic??? Picture included for reference…

 

Hey Iccy:

They are the main power/ground buses to the fuse/relay panel.

I think these are as follows:

30 - 12V Power all the time
31 - Ground
X - Switched from Ignition (position 1)
15 - Switched from Ignition (position 2)

Look at the wiring diagrams, Section 97, Page 2, A16 and Page 8, B73 thru F73.

Comment: The wiring diagrams for these cars are the worst I have ever seen. There is no way that Porsche used these diagrams to build these cars. I've been trying to troubleshoot a problem with my backup lights and PRND232 lights, which use the same power source!, and the wiring diagrams from page to page contradict each other. What a PITA!

 

Those are 'standard' bus numbers. Look on the early pages and see where they get power.

15 gets power from the ignition switch when the key is in 'run' or 'start' position
30 is unfused battery positive, on all the time.
31 is ground
50 is true when the key is in the 'start' position
X is true when key is in 'run' position, but drops out when key is in 'start' position.

The others you'll need to trace bacv k to their sources on the drawing. What year is the car?

 

The car actually spans multipul years... many parts have go into making this project. Basically it's a 1980 Euro S K-jet car from a wiring standpoint. We're removing everything that's not needed to avoid electrical gremlins down the road. Right now we're tracing and testing every circuit. Thanks for the feedback guys - big help!!!

 

Bill, if you have the CD set from Jim Morehouse, there is a set of supplements about Electrical Training. In one of those documents it describes these codings. They were standards for automotive at that time, maybe still. Although it doesn't say much more than what others report, above, you may find other such number designators that you need to decipher and want a ready reference.

 

Chris, I did flip through Jim's CD with the electical training but I didn't see that... I must not have looked close enough - thanks for the info, will give it another look.

 

There are at least four of them on 2.15 CD1, sub tab Electrical, having file names interlaced enough to be confusing.

The one with this information is entitled "928S Electrical Troubleshooting and Repair.PDF"