crazy electrical problem

I have a crazy intermitant electrical problem in my 81 911SC. Occaisionally while driving the tach will jump around from 0 to 7,000. At the same time all power to the radio will be lost and some times, not always, the light above the parking brake indicator will come on, as in when the Ign. switch is in the run position without the engine running. Sometimes when all this is happening the alternator light will also come on. The crazy thing is, if I depress the clutch pedal all the way it will temporarily stop doing all this. Anyone have any Ideas??????

I'll bet you have a faulty ground somewhere. Maybe take a look up under the dash and see what the lever arm of your clutch is hitting, maybe some bare wiring. I had a myriad of elec probs with my car, and that's sort of how it acted when I wired something wrong...

[Wayne 962]

Make sure that your ground strap is attached well from your drivetrain to the car. It makes no sense that the clutch being pressed in would solve this problem unless there is a contact being made when the disc is unengaged.

A bad ground strap could be responsible for other bizarre electrical problems as well. You might want to check the resistance from your tranny to the battery neg. It should be pretty low (ohms).

Hope this helps,

Wayne

Just before my CDS unit went south, my tach started to do the same thing i.e. jump around like crazy (but only intermittantly).
Then one day it wouldn't start at all...There
is a section on troubleshooting CDS in the Haynes manual...You might unplug unit and check pins on connector for corrosion...also unit will make a whistling sound when powered up, this is capacitor loading. You might hook up up voltmeter (+)to ground on interior light (?) and (-)to solid chassis ground and see if you have voltage on ground side of light. If it does turn out to be CDS, I have had good luck with MSD ignition system...Sean

[kenikh]

I just thought that given the discussion in this thread...

http://forums.pelicanparts.com/porsche-911-technical-forum/58159-mud-flaps-911-what.html

...that it would be fun to bump a REALLY old thread.

Dude, May 1998. I still hadn't found a job after graduating from college, a Playstation (1) was still cutting edge, Napster wasn't even a thing, Radiohead was touring OK Computer...and I still cared about Radiohead. And Wayne actually still posted on the Forum.

Most importantly, I was still 8 years from owning my first Porsche, the 1969 911S I bought in 2005. How 17 years fly...and oh, how the cars accumulate! I'm proud to say, I've still never sold a Porsche. I don't have the heart.

Enjoy the nostalgia!

Confession...I still care about Radiohead