Starting problem

[928jr]

Hi Guys,

I was hoping someone could tell me what electrical items are connected via the loom that runs along the back of the spare wheel well, I've started having some really annoying problems that I think can be isolated to these wires.

I've recently begun to have issues starting my 928, all the other electrical items will work when I turn the key, but the engine does not even begin to turn over.

I think it may have something to do with the wiring loom that runs along the top of the spare wheel well, if I wiggle it a bit, the problem usually disappears for a while and will start first kick again.

Also worth a mention, on the odd occasion the speedo will hit 160k and the engine fan will start before the engine has even turned over, these both return to normal once I start the engine

I have had to remove the spare a couple of times in the past 6 months after the alternator died, in the process I think I might have damaged that loom.

Cheers in advance!

[928jr]

I'm pretty sure this picture below is a diagram of the wiring harness I am having troubles with. In the second image I have outlined in yellow the section of my wiring harness that I think might be damaged.
Worth a mention, I've carefully cut a slit in the outer cover of that loom to check for internal cable damage in the yellow highlighted section, but I haven't found anything to date.

I'm fairly new to this car and so I'm just getting the hang of where things are and what could be causing what. This diagram doesn't give me any information on where these cables lead to and what each end connects to. If anyone has or knows where I could find such a diagram that would be great!






Cheers

[AirtekHVAC]

Not sure what the circuit is, but corrosion is common on the connectors. You perhaps might need an ignition switch. Also a very common failure point.

[928jr]

Good point, I must admit there are a few corroded contact points that I am in the process of cleaning up, I hadn't thought to check the connections in this harness.. might explain why the problem disappears when I wiggle the loom around too.

I've heard once before that the 928 ignition switches are a common failure point, I've done a search and it seems to line up with some of the symptoms that my car is having. I'll look into this a bit more if I have no luck cleaning up the connections.

Cheers

[AirtekHVAC]

I am no pro, but am at the begining of a restoration of a 78. I was also directed to check the 14-pin connector under the hood...it is also a very common corrosion point....it is right next to the jump point (12v) connector.