Late 1995 w/ Immobilizer. Random starting issue

[Black993c2]

Hello,

I'm posting on behalf of my father who has a late model-year 1995 c2 that has the factory immobilzer in it. The car sat for about a week and a half earlier this year (usually daily driven) and has since had trouble starting on and off. Sometimes it will start without issue, others it will not try to even crank over. Battery has been test/replaced, the immobilizer/ECU has been replaced 2 times with parts from Porsche of Orlando as well, and the key fob battery has been replaced, and tested with the 2nd key fob that came with the car. The car is at an independent shop currently and has been for 3 weeks while trying to source the cause of the issue.

Prior to this, my father had mentioned he saw a key fob light that was lit on his dash (which I assume to be the immobilizer indicator light in the clock). Still trying to verify if this is still lit.

When the car does start, it starts and runs as it should. The mechanic can start it numerous times, but eventually it will fail to start (usually after they tell him its fixed and he arrives to pick it up).

Grasping for ideas as the shop has no idea what the problem is at this point. I did a bit of research and it looks like most threads are for cars that crank but do not start. The ones that do relate to this issue seem to never have any follow up info. I don't believe it to be DME related as the car doesn't even attempt to crank. Thinking it must be related to the immobilizer or ignition switch for it not to even attempt to start.

Would greatly appreciate any thoughts or possible causes.


Thanks,

Justin

[TMc993]

Some things you did not mention that I would do before thinking about purchasing a new ignition switch:

Check the starter relay (R61), not the DME relay (R53). The horn relay is identical so if the horn works, a simple swap is an adequate check.

Remove and thoroughly clean the ground cable connections where the cables on the battery and starter attach to the chassis.

If the battery ground cable is the factory original woven-wire cable, it would be a good idea to install a new ground cable as the woven cables corrode internally and fail.

Check the clutch pedal "ignition interlock" switch (Assuming the car has one) to make sure it is functioning properly.

When the "non-start" condition is present, check to see if current is present at the starter when the ignition key is turned to the "Start" position. If current is present at the starter, then the issue may be the starter itself.

Hope this helps.

[wesleyc]

I feel your immobilizer pain ! I bought a late year 95 in November that had the drive block on it. After having my early year simple non immobilizer 95 for a few years the immobilizer drove me nuts. It worked when it wanted to ? I would try what TMc993 suggested. If all else fails you can bypass it. Good luck !

[S ECU Repair]

I really like TMc993 suggestions. They are spot on.

The Immobilizer Drive Block system can be bypassed, but all those other elements (Relays, Ignition Switch, Grounds, Clutch Switch, Starter) need to be in tip top shape before you can consider any other options.

Let us know what the Indy shop says...