Hotwired SC Starter, replace igniton switch?

[JB81SC]

I have owned a 1981 911 SC for the past six years or so. The previous owner mentioned a “hotwire” switch in the engine compartment installed by his previous owner. In the past, very infrequently, when I turn the ignition switch power was sent through the electrical system, however, the starter did not turn. No big deal, just pop the hood and hit the magic switch and off I go. This season, the ignition switch will not start the car at all, requiring the pop the hood trick at every start. The “hotwire” switch is located next to the oil filter with two leads passing under the engine to the starter.



When the ignition is on and the switch is depressed the car starts. When the ignition is off and the switch is depressed the engine turns over but does not start. At this time, I assume I need to replace the electrical portion of the ignition switch. Pelican Parts #M-613-012-00.



Am I correct with my diagnosis? If so, how difficult is it to replace the electrical portion of the switch? There are a ton of wires in this area and I haven’t tackled digging through them yet. However, it looks like there must be a cap, with the wires attached, that slips onto the electrical portion of the switch. The electrical portion must be attached to the ignition tumbler with two screws. Is the work done from behind the dash? Any tips would be greatly appreciated.

Thank you,

Josh

[makaio]

To replace the electrical portion of the switch is no problem. The hard part is craming yourself under the dash.

Before you change it out, I would check all connections, and ground contacts for cleanliness and corosion. My guess is the starter solenoid has been going bad, and the hot start switch in the engine compartment was put in as a band aid.

[yelcab1]

Removal of the seat makes it a bit easier to lie on your head, upside down. I used to be able to do this on my 84 without removing the lock cylinder. I am not able to do this with my current SC. Don't know why.

[Superman]

I recently had similar trouble, and it turned out to be the connection at the 14-pin connector that is on the engine compartment fuse panel. The wire in question is yellow, at least on my car.

[RoninLB]

Originally posted by Superman
I recently had similar trouble, and it turned out to be the connection at the 14-pin connector that is on the engine compartment fuse panel. The wire in question is yellow, at least on my car.

my car also has an AC compressor clutch "T" take-off in the trunk behind the gauges for more electrical fun. This is also the routine place that aftermarket starter kill is located with a relay.. needless to say that the yellow solenoid ignition sw wire takes a convoluted path.

personally I think that any 911 ignition sw with over 100k mi is a prob waiting to happen.. that said, I'd jump battery hot directly to the yellow wire at the ign sw, after disconnecting it from the sw, and see what happens. I'd use at least a 12ga wire to jump.

[JB81SC]

Matt & Yelcab1,

Thank you for your replies. Obviously, a previous owner had a similar issue to mine and it has only progressively gotten worse. Both the electrical portion of the ignition switch and a starter solenoid are inexpensive fixes. Why would anyone go through the trouble of adding a hot switch to save $50.00? The starter solenoid theory sounds good to me, am I missing anything? Is there any way to test both the ignition switch and the starter solenoid to be certain?

Thanks again,

Josh

[RoninLB]

Originally posted by JB81SC
Is there any way to test both the ignition switch and the starter solenoid to be certain?

read my 2nd paragraph above again.

if the engine comp sol jump operates the sol then it's ok.

I installed an eng comp sol jump to make spinning the starter easier when working on the engine and as a back-up.

[JB81SC]

Superman,

Thank you for your tip!

Josh

[JB81SC]

RoninLB,

Thank you for the reply, your insight and the expanded explanation. I sent my first reply before reading your initial post.

Take care,

Josh