928 S2 Starting problem

[James Hewitt]

I have a 928 S2 1986 model, it does not start with the key.

It sometimes starts but can not predict what contributes to this.

I have checked the ignition module, the starter motor, the immobilizer and the relays. Even checked the electric current upto to the starter motor clutch.

Turning the key does not engage the starter motor, although I can start the car if I hot wire the starter motor (with the key in primed position).

Can some one give me any ideas as to what could be the problem

You can contact me direct at sa@trader4ukcars.com.

[rich]

I'm not familiar with the switch design but if it's anything like the 944's or other porsches I would be suspect the electrical rotating part at the base of the key is failing. Also, is your car an auto? Check the park switch in the shift console.

[Danglerb]

Originally Posted by James Hewitt

I have a 928 S2 1986 model, it does not start with the key.

It sometimes starts but can not predict what contributes to this.

I have checked the ignition module, the starter motor, the immobilizer and the relays. Even checked the electric current upto to the starter motor clutch.

Turning the key does not engage the starter motor, although I can start the car if I hot wire the starter motor (with the key in primed position).

Can some one give me any ideas as to what could be the problem

You can contact me direct at sa@trader4ukcars.com.

When you turn the key, sometimes it starts normally, other times it fails to crank the engine, but if you jump the starter directly it starts?

If so that means the ignition circuit is getting power, but the starter motor is not. Work backwards from the starter until you find the part with power on one side and not the other. It may be easier to just round up the usual suspects and replace them in lowest cost first order.

Fuse
Relay
ignition switch

My car turned out to have two alarm (immobilizers) systems, the factory and a troublesome aftermarket unit. Once the second alarm system was removed the problems went away.

[Alan in AZ]

James,
Most likely issue is the Starter Relay - swap it with the horn relay and see if that helps - next most likely is the electrical part of the ignition switch. See if you are getting power to the relay coil (pin 86 of the starter relay socket) while the key is in start - if no - your ignition switch is fried... Since its intermittent you will need to try these tests repeatedly...

BTW in this case there is no fuse...

Alan