Ignition Switch Troubleshooting
 

Can anyone clarify when there is a problem with the ignition switch if it involves replacing the whole switch or just the electric coupler that is attached to the back of the mechanical part of the switch. In my 1973 911 I am experiencing intermittent failure of the starting motor to engage. In the start position the starter will not engage but with a wire from the solenoid to 12 volts and the key in the run position the engine will start. In the past I have replaced the whole switch but with the high cost of the part and the new key and matching other locks if it were only the electrical part the expense and hastle would be greatly reduced. Thanks for any input.

Well....you've elimated the starter as the problem....
But now it's down to the wiring or the switch.

You can test the wire in the car with a VOM meter, or you could jump power to it at the switch location to eliminate the wring.

If it's not the wire, then it's in the switch. As far as I remember, the electrical section is completely seperate from the front half "key" section. So if your key is still tuning the electrical section you're lucky....get the cheap part and it's a lot easier too.

(I, on the other hand, had the little male section that goes into the electrical section fail, so i need it all. Grrrrrrrrrrrrrrrr.)

I just went through this on my 73T. Starter would work when cold, but was intermittent once engine was warmed up. I replaced my starter with the lighter weight hi-torque aftermarket unit offered here (an excuse to lose 8 net pounds and replace a 33 year old starter). The problem persisted so I checked for 12 volts at the starter solenoid with my volt meter, definitely intermittent. So, I replaced the electrical portion of the ignition switch, problem solved. The ignition switch electrical module is easy to replace, just pull the plug on the back of the switch and remove 2 screws (access is tight for the top screw location); the module pulls right out.

Good Luck,