Unused cable at Voltage Regulator - 1968 912

[dizzycap]

Hoping someone might just know this. A small part of the wire harness in the engine bay on my 1968 912 was fried long before my ownership (I promise!).

It’s two cables coming out of the main loom together at the left hand corner and one is the thin solid blue that attaches to the voltage regulator 61, coming from the generator light in one of gauges.

It’s the second cable that I can’t quite figure out. Thin solid yellow, and not dissimilar in length to the blue that goes to the voltage regulator. This one has fried, but it did look like this one was tucked back on itself in this part of the loom, which I think Porsche did with option-type cables that were surplus. It’s yellow so I am thinking it’s for a light of some sort (optional reverse light? Optional engine compartment light?).

Any suggestions on where I should start my investigations for the other end of the cable up in the front boot are welcome

[Nine One One]

Speak with Max at Revival Cars he should be able to help you out

[wildtexas]

It connects to the starter motor on a 912. Not sure of its purpose in the 911 loom. With the ignition switched on it can be used to start the engine from the engine bay by touching it to live on the voltage regulator. Can’t remember which terminal off the top of my head.

[wildtexas]

Not sure why yours is fried…

[dizzycap]

It connects to the starter motor on a 912. Not sure of its purpose in the 911 loom. With the ignition switched on it can be used to start the engine from the engine bay by touching it to live on the voltage regulator. Can’t remember which terminal off the top of my head.

Thanks! With that info I found it straight away, both in the line diagram and even found a pic of the wires on the internet!
The cable is for the starter relay. And mine wasn’t connected at all. I will have to look into that.

Last picture of first post in this thread:
https://www.early911sregistry.org/forum ... s-Analyzed

[AndrewSlater]

I don't believe the 912 has a starter relay.

I think that on a 911 the yellow cable was to energise a relay to short out the ballast resistor for the coil, ensuring maximum coil voltage during starter turnover.

On the 912 you can use the yellow wire to touch on the B+ terminal of the voltage regulator, to allow you to start the car from the comfort of the engine bay ( assuming ignition is switched on ). Used this useful 'feature' many times.

Hope that is all correct and helps.

Andrew

[dizzycap]

Thanks all!
Yes, you are correct, it’s not a starter relay as such, it’s the ballast bypass relay.

On 912s there is no ballast resistor, right? Where would this yellow cable attach on 912s? Or is it just tucked back on itself and left in the air?

[wildtexas]

It doesn’t connect. It just sits there confusing us. Very useful for remote starts when you are looking to fiddle in the engine bay.