Hello all:

I have been trying to pin down a cooling fan issue in my 928 S4, with little success so far. I have read a few web sites that refer to electrical issues causing some problems with the fans, and I know that my voltage readings are low according to my mechanic. So, I want to try to troubleshoot my electrical system from the battery forward and see if I can pinpoint bad wires, relays, etc., and see if I can eliminate that as a cause (also, I plan to put a more robust stereo in w/amplifiers and I think I need a well tuned electrical system for that as well).

Here is the problem: I am a total newbie with car electronic systems. The articles I have read refer to checking the voltage at various points in the car, infinite ohms(?), and the like, and it is a bit confusing. Does anyone have knowledge of a source of information for the 928 electrical system that is geared toward someone like me? An electrical diagram I don't think is enough - I need a bit more remedial education

Anyway, if anyone has any information to provide you would make a new shark owner very happy (and smarter)

Bill

 

Bill,

PM me your email address or post it. I can email a document I put together going over electrical basics of the 928. Too much of a PIA to post it here due to pics.

 

Bill, Fluke.com is a good start.

http://www.fluke.com/application_not...AGID=1&SID=103

 

Bill,
This may be a tough choice of car to learn on though - it has a heck of a lot more complexity than most others of the same era.

I'd suggest you do get the manuals/schematics since its just too confusing to do much of anything without them (even if you are otherwise qualified).

Also be very wary of any aftermarket add ons - almost none of these seem to have been installed completely correctly - often due to poor knowledge of the cars electrical system (something to do with the manuals costing $350). I'd suggest trying to temporarily disable enything that isn't stock to see if this remedies any ailments (although this may be hard to do also).

Good luck...

Maybe you can ask a very specific question about what you want to do and I'm sure you'll get specific help from this board... general knowledge is hard to impart - "testing the alternator" can be described though....

Alan

 

Rez,
do you think the writeup you did should/could be included in the 928 Technical Publication cd's? Although most of the manuals are Porsche technical training publications, there are a few writeups by individuals. If you'd like to have it included, please email me at jim928@ptd.net.

thanks,
Jim

 

Bill

First thing on the 928 from an Electrical perspective is to ensure that all the Earth points are cleaned. Do a search for Earths or Electrical and I'm sure it will turn up Wally Plumleys "annual elec maintenance schedule"

Re Fans

I am reasonably convinced, bad contacts/earths and pure physical damage permitting that the fan controller system is very robust. I chased what I thought was an electrical/electronics problem with the fans for about 6 weeks (I know my way around electrics and my wife is an electronics engineer so I have a reference if I need it) to discover that the problem lay in the fact that the fan motor bearing were toast. You will not pick this up by any amount of electrical testing short of (excuse the pun) disconnecting the fan from the car and applying 12v across the terminals and thenwondering why the fan manages about 1 rpm. Check this first! With the ignition off and a cold engine spin the blades with a finger a gentle flick should make the fan turn smoothly and continue for at least one turn stopping smoothly and gently. A "sudden" stop indicated bearings that are toast.

Gentle hint - knowing the symptoms of your specific problem will help us point you in the right direction, or allow us to ask you to test a,b, or c!


Cheers
Jon
Black SE

 

Jim,

It's mostly copied info. I couldn't remember where I got, but SteveG posted it... Fluke. I just made it into a word doc. which I found easier then lipping between pages on the net.

Then added some 928 stuff to it.

I'd be lying if I said it was original stuff.

 

I found a tracing tool very useful - usually used in networks and office wiring situations. A sender unit attaches to a wire, and can send a tone (steady note) or a warble(up/down noise). You then listen for the tone by induction with the other part running along the outside of the wire, moving either away from the sender if trying to trace where it goes, or from where-its-supposed-to-go back towards the sender to find out where the wire is broken or shorted. Very easy to do single handed, dont need long leads on a meter etc.
jp 83 Euro S AT 47k