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Electrical gremlins

Posted: Wed Oct 12, 2022 5:03 am
by aerolithe
Good day all

I got a 1986 944 non turbo that I bought not running. Now she is running but I can't figure why the wiper, blower, fog light, reverse light and window do not work. I found under the fuse and relay tray on terminal block K a green with red strip cable which is burned but after trying to find where it goes .... I just don't see where it connects. Any help will be really appreciated. I try with the Haynes book to follow the wiring diagram but not clear to me. Anyone have a correct diagram for my year?

All the best and happy motoring

Re: Electrical gremlins

Posted: Thu Oct 13, 2022 8:02 am
by Tom
aerolithe wrote: Wed Oct 12, 2022 5:03 am Good day all

I got a 1986 944 non turbo that I bought not running. Now she is running but I can't figure why the wiper, blower, fog light, reverse light and window do not work. I found under the fuse and relay tray on terminal block K a green with red strip cable which is burned but after trying to find where it goes .... I just don't see where it connects. Any help will be really appreciated. I try with the Haynes book to follow the wiring diagram but not clear to me. Anyone have a correct diagram for my year?

All the best and happy motoring
Sorry, I missed this. Let me pull up the schematic.... Stay tuned.

Have you checked Relay X? The burned wire would still need to be sorted out, but that relay powers all the things that aren't working on your car, so seems a likely culprit....

Re: Electrical gremlins

Posted: Thu Oct 13, 2022 10:16 am
by usury
aerolithe wrote: Wed Oct 12, 2022 5:03 am I try with the Haynes book to follow the wiring diagram but not clear to me. Anyone have a correct diagram for my year?
You probably don't want to rely on the Haynes manual, in general, when the official Porsche Factory Service Manual is available as a set of PDF's (via Google search, or I believe the Facebook "944 no spam" group has those and other documents in its file download section).

Complete schematics by model year are in "Vol4 Electrical pre88" and "Vol5 Electrical 88onward" of the FSM.

Porsche wiring diagrams are tricky to read at first. I think I learned how from a YouTube video.

The color abbreviations are in German. Like SW is Schwartz, which is black. And RT is Rot, which is red. A Google search for "German Wire Color Codes/Abbreviations" ought to point you in the right direction.

It also helps to Google "Bosch Terminal Designations" to get a handle on things like KL.X and KL.30/31/15, etc.

If you spend some time with the schematics, it will start to make sense. And people here can help.

Re: Electrical gremlins

Posted: Thu Oct 13, 2022 2:32 pm
by aerolithe
Good day

I work on the car today and fix the fog light by bypassing the fuse. It looks like I don't have power coming at the fuse terminal. I print some diagram but could not find the Vol4 Electrical pre88 page 2
Appreciate the help
Marc

Re: Electrical gremlins

Posted: Thu Oct 13, 2022 7:23 pm
by Tom
aerolithe wrote: Thu Oct 13, 2022 2:32 pm Good day

I work on the car today and fix the fog light by bypassing the fuse. It looks like I don't have power coming at the fuse terminal. I print some diagram but could not find the Vol4 Electrical pre88 page 2
Appreciate the help
Marc
Not sure how much this will help, but here is that page.... After poking around a bit, I'd definitely check Relay G14 (aka Relay X). It would explain no power to the things that are not working I believe, but not the burned wire. What size is the green/red wire? I see a .5mm (small) wire in that color going to A10 of the climate control module, but suspect the one that burned on your car is bigger?

Re: Electrical gremlins

Posted: Thu Oct 13, 2022 7:31 pm
by usury
I don't know if it's okay to post copies of the FSM here, but my copy sems to have all the electrical schematic pages for your 1986 model.

If yours doesn't, PM me and I'll help set you up.

Other non obvious things you'll find in the schematics:
"Central Electrics" is Porsche schematic speak for "fuse box".
ROW means "Rest of World" (whereas US-market models would otherwise be assumed).

Also, have you confirmed that "Relay X" is working properly, as Tom suggested? You'll find Relay X in the Central Electrics schematics.

Re: Electrical gremlins

Posted: Sat Oct 15, 2022 4:54 am
by aerolithe
Good morning gentleman

The X relay was not operating properly, I actually change it and now the blower and wipers, window do work.
I still have to figure the reverse lights.

Thank a million

Marc

Re: Electrical gremlins

Posted: Sat Oct 15, 2022 8:37 am
by Tom
aerolithe wrote: Sat Oct 15, 2022 4:54 am Good morning gentleman

The X relay was not operating properly, I actually change it and now the blower and wipers, window do work.
I still have to figure the reverse lights.

Thank a million

Marc
Awesome! The power of Pokes! Worth digging to see what the burned wire does/did. Check fuse 28 for the reverse lights. There isn't much to that circuit after relay x -- just the fuse, reserve light switch, and the bulbs. If all those are ok, it must be the harness and/or connectors/sockets.

Re: Electrical gremlins

Posted: Sat Oct 15, 2022 6:51 pm
by usury
On my 1987, the reverse light is activated by a not-so-easy-to-reach switch on the transaxle.

I replaced mine when it failed about five years ago. Something is making me think that not all models of 944 have the transaxle switch, or that maybe the backup light circuit works differently for early vs late 944's? Regardless, a switch somewhere has to recognize the car being in reverse.