MGW-Fla

After a two cocktail lunch no less right??
Hey Mark, can you loan your mechanic over here??

Mark

Mel - he was with me at the Rolex 24!

H2

Looks like really gray spagetti. I don't think I'd ever be able to get it back together.

H2

Alan

Why all grey- who knows - probably figured that customers would never get that far into it. There are also no schematics (with color designated wiring) for the panel as a whole...

Its actually fairly straightforward to trace things but its a tight fit - the nest of wires gets in the way of the relays - for example removing the coinnectors to replace a socket!.

I wish Porsche had created some kind of wire organizing device on the back (pins, hooks, channel whatever) to run the wires a little longer but orthogonally and not randomly crossing the relay socket area. This would help a lot...

When I rewired a bit and added some new relays I did use color coded and functionally tagged wires...

I guess they never anticipated a panel would get modified after installation...

Dave the non-hinging is more a function of the wider panel and the interference with the LH & EZK - the panel could hinge - the ground straps are certainly long enough - but there is no clearance.

Granted the new relay sockets are a challenge (especially the small corner pins... Don't mess with them!) but they do also have more pin options.

Alan

mpesik

How the heck do they get the wires so tight in there? I doubt if they cut to length first.

FlyingDog

Midget laborors from eastern europe.

mpesik

mpesik

Anyway you look at it..which is probably in only one way, it's crazy what goes on back there!!!

And I'm scared!!!!!!!!

SharkSkin

Early wires were black -- maybe they went to grey so it would be easier to spot heat-damaged insulation.

I agree, Alan... they could have used better wiring management. The back of that panel looks like of like one of the old server rooms I used to work in. I'll have to look closer at your PDF... I didn't realize there were any relay pin layout schemes on the later cars that were different than on the early ones.

BTW, the wires probably were cut to length individually and hand-fitted. We're lucky they didn't use pins & wire-wrap.

Alan

Dave the relay socket difference is that on 77-84 the sockets had only 7 pins while the 85+ ones can have the full matrix - up to 9. Now those extra holes probably make them less rigid too ... so take your pick.

I don't believe Porsche actually developed any relays with more than 7 pins but the option is available.

I wish you could buy empty relay base cans with a solder tag array base inside - great project encapsulation mechnism - I've looked but no one seems to make them... don't know why...even just 5 pin basic relay footprint versions would be handy.

You can make your own by buying a relay - opening it and sawing the guts out - not very convenient - been there recently! but at least its only $2-$3 for a generic bosch type.

Alan

SharkSkin

I've thought about that too. I think I have a few medium-height relays on my spare panel, maybe I'll take a look at that. The interior light dimmer would be an excellent candidate for that. OTOH, I have to make one connection inside the panel and three outside for that project. Decisions, decisions.

I meant to say earlier, about hinging forward... I keep forgetting about the brains being in the way too. But mostly I was referring to the main power taps being on top. Some of my troubleshooting adventures have involved tipping the panel forward and probing the live circuits/relay pins from the backside. That would be quite a bit more complicated to pull off on a later car, for both reasons.

John Struthers

The LCU must GO!
You gotta figure that there was a bit of weed/hash/hash oil involved here somewhere.
I can remember solving all the problems of the world back in the late 60's with a little herbal assistance.
Girls gone wild! Electrical engineers gone wild! All the same in theory.
Apparently a older, wiser team manager was not available when the 928 wiring was approved because they surely missed the basics of production efficiency, ease of repair, and simplicity of design.
On the upside, Porsche maintains a brand unique quality - er, quirk - by offering splinters of German wood to the 928 owners at no extra charge.
Do you suppose, by any chance, there was a Porsche Jaegermeister?

Alan

Dave,
The reason I was hacking up relays was to make a relay test kit...

I have a relay with the guts totally cut out - 2 LED's to show coil activation (though there is no coil now).. It also has a mini SPDT switch operable from outside the can so you can switch it manually.

I also am working on a fully working SPDT relay with a ribbon cable snaked out (approx 15" long) that terminates in a small plastic box with status LED's for the coil terminals and each of the switch terminals. It presumes one side (either one) of the coil is grounded and that one side of the coil or any switch terminals is @ ~12v (much more than a fair bet although still not guarateed).

It then shows for each pin if its @ 12v or 0v (LED for each - floating if both off).

Voila instant relay test kit - unfortunately its only good for std SPDT relays.

The 3rd component - not done yet would be an extender - 7 pin relay base wired vis a probe pad to a 7 pin relay socket on the other end (probably ~24" long w/decent gauge wiring). If in doubt pull the relay - mount in the extender and proble the pins on the back with a DMM while its working

For headlights etc you'd need 2 of these...

Still in construction on all these (way too many projects... and these are low priority)

Alan

SharkSkin

Alan, I've made an "extender" by simply making a set of 6" long wires, each with one male and one female blade connector. Not as fancy, but gets the job done...