drwhosc

Help me understand how to locate a short in my wiring harness. Granted not a 928, so the electrical system should be simpler. I have a 85.5 944 non turbo. My issues started years ago, when my hazard switch smoked. I cut back in the harness and found some burnt wires. Replaced those, and got about 3 years out of that fix, but now my potentiometer smoked, so OUCH. Still have a short somewhere.

I pulled things apart, and said crap now what! I really do not know how to trouble shoot a short. I decided to go to the wiring diagrams. And I looked at the hazard switch. I have not seem anything like the internals of this switch. My initial issues started her, but I can not figure out what is on and what is off with different switch positions. It looks like it is fundamentally switching the grounds between two circuts.

So need to understand when hazards flashing what is on. And when hazards in turn signal mode, what is on and if the ground changes.


Hazard warning switch wiring

15 → Power fuse M8 also Spare connector A22
30 → To Concealed headlight motor (Pos 1) Via Fuse 2 (25A) and L41 (CE)
49 → Flasher 49
L → to Flasher Bulb via Fuse 31
R → to flasher bulb via fuse 32
58b → Cigar Lighter bulb to Potentiometer
31 → Grounds (Lots) MPIII
49a → flasher 49a

OK so back to my stor. I have a short in my 944. It was melting my Hazard switch. dimmer switch. I opened the wiring harness, and repaired the obvious. Put back together, now it is melting my potentiometer. So the short persists.

Here are the symptoms now.

The hazard switch will have a low red glow when it is on. The turn signals will work R & L. Melts potentiometer when plugged in

Hazard switch off, turn signals flash, I get a buzz in the flasher when driving

I took the harness back to the bulk of the repair, and no new damage.

The potentiometer has two inputs

1-> 58b via cigar lighter bulb which is also connected with the Instrument cluster bulb. The ground is going to CE12(31) via MPIII

2→ Clock lamp Glove box light via light switch (56) via fuse 38 There is a second wire going to a “bridge Adapter” BRUEDKEN

So power is getting into this circuit now ….. Oh and my blower fan is also activating…. May or may not be related in this hurting electrical issues car.

waynestrutt

Clean the grounds and tighten them, replace broken or loose connectors and oxidized (blackened) copper wire, Get some Deoxit.

drwhosc

Thanks for the email. That was a huge help. Definitely will
Do this as well. Did it on the 928, but not this car. Will also check the light sockets for corrosion