mgabrielf

Hello guys,
I have one 1984 928s,
I'm having a lot of electrical problems with it, and this forum has helped me a lot to solve many problems, but wen I was cleaning all the ground points of the car, in the trunk I found a loose cable and could not find what this is for, in case this is one connection of two brown wires and one brown with white and the output is one brown and a brown and white, this cable is not of the opening trunk engine, it is not the windshield wiper engine, I can't identify it.
Any suggestion?...

missing wires

linderpat

Does your license plate light work?

dr bob

-- Brown is always ground to chassis.
-- Brown-white is used for "rear lid switch" at coordinate 21 on circuit diagram VI for the 1983 car. This is actually the rear hatch switch that turns on the rear courtesy (interior) lights when the hatch lid is not closed.
-- Brown-white is also used for the "interior light rear" and the "interior light rear lid", common to the switch wiring. See coordinates 16 and 17 on the same 1983 circuit diagram VI.

The 1984 circuit diagrams are poor, and show no wire colors. Fortunately, most of the body electrics are consistent between these years. The corresponding circuit is shown on the 1984 diagram at coordinates 22A through 22C, on 1984 circuit diagram 4 in the workshop manuals, for reference.

And Welcome to Rennlist!

Mrmerlin

Nice writeup Dr Bob.

dr bob

At some point, we'll need to build a database of wire colors and uses for the various years. It would make things a lot easier if we could just go to that handy cross-reference and see which wire colors are associated with which functions. Add some connector info like connector number and pin number within the connector. Then location info and maybe a picture of each connector in a car. It would take a lot of the excitement out of electrical troubleshooting.

mgabrielf

Well said Dr bob, the circuit diagrams are really poor!
thank you for your help,
:-)

gomez123

The workshop manuals have very nice diagrams. I was fortunate enough the receive an entire set with the purchase of my first 928.

dr bob

The usability of the diagrams varies from year to year, and by which medium you receive them. Earlier printed WSM's have some of the diagrams printed in color. Later editions have them on B&W. The designers who drew the first few years of diagrams came from the same school that educated VW, and other Porsche model electrical designers. Between 1983 and 1984, there was a shift in how the drawings would be laid out. The 1984 drawings in color aren't too bad, but but it was still a "learning" period for both the designers and their victims: the folks who work on the cars. For those who had grown up with the previous layouts, suddenly there are hard-to-follow links. The indexing system changed from page-and-function based circuit lines to a full-set reference system. Note how the numbers in the vertical increment from page to page rather than only within pages. This is a more industrial method, maybe needed as the wiring and functions got more complex. Regardless, finding stuff and tracing current flows and functions in the 1984 drawings is tedious at best, and a real chore if the drawings are in black-and-white; there are no wire color designations on the black-and-white versions, and that includes the scanned sets. Best option is to look at the 1983 and the 1985 drawings and work back towards the 1984 to see which border year drawing is closest. Fortunately, the wire coloring scheme is relatively consistent among the years. For body wiring, the colors are very consistent among these years. The Good News is that by the 1986 drawings, there was at least a consistent standard way of showing circuits, links and wire colors that continued through end of production.

Alan started a massive project of decoding and describing some of the particulars about reading the drawings. This is something that really needs to be a community effort with a project coordinator, rather than a one-person effort. It's just too much work for one person to do it all.