imdvs

'96 C2. Car is locked, I unlock it with the remote. When I insert key in ignition I hear the sound like the door automatically locking. Turn the key, locked out no start. Remove key, go through lock unlock procedure, insert key in ignition, get thumping lock sound again and once more no start.

I have gone through this routine as many as nine times before it doesn't lock me out.

Other times no problems, works normally. New batteries in both remotes.

Any ideas?

Jay777

Interesting. A little more information please:

1) When you hear the "sound like the door automatically locking" can you confirm this happens at the exact instant the key is inserted?
2) After the sound, do the door LEDs flash like they normally do when locked with the FOB?
3) Is the thumping sound less pronounced (sort of muffled) than the sound you hear for a normal lock-with-FOB (with LED confirmation)?
4) When you remove the key, does the first actuation of the FOB lock the doors and the second unlock them?

imdvs

Thanks, jay777, I'll go through the start procedure and report back.

Lorenfb

This problem more likely to occur from the alarm ECU than the immobilizer.

imdvs

1. This does not happen until key is turned.
2. No.
3. Yes, definitely muffled sound.
4. Yes, lock then unlock.

Jay777

OK, good. A couple followups:

1) What position does the key have to be rotated to to get the muffled lock sound?
2) Do the door LED's do anything at all when the you get the muffled lock sound? If so, what do they do?

imdvs

1. The locks make the muffled sound when the key is turned to the first stop, ACC
2. The door LEDs do nothing.

993/907

Ignition switch can wear and send stray signals to immobilizer. Symptoms can vary and be intermittent.

ekimerpud

Do both of your electronic door locks work? I had an issue where the locks would cycle when I pressed the remote button, and it turned out my passenger door lock actuator was faulty. I replaced the actuator and it solved the lock cycling issue.

imdvs

Yes, both doors lock.

Jay777

Unclear what the problem is with the information provided but the "muffled door lock sound" is a good place to start. First, the muffled sound happens when the Alarm Control Unit (ACU) tries to unlock an the already unlocked door. (You unlocked to get in and when you rotated the key to "Accessory" the ACU "unlocked" it again). The Immobilizer has no wire connection to Accessory power (vehicle "X" Bus), so doesn't know, and can't do anything, based on the X bus turning on, i.e., sending an unlock pulse to the ACU. That, plus the fact that the FOBs seem to work (your next 2 FOB presses LOCK then UNLOCK the doors) points suspicion away from the Immo. That leaves the ACU. The ACU also has no direct connection to the X bus but it does interface to lots of things things that do. Is there some combination of signals that normally tell the ACU to unlock the doors? If so, it would be a great place to start looking for intermittent connections, faulty component, etc. Unfortunately I don't think that the ACU is ever supposed to unlock the doors other than from FOB presses. Anyone? If that's the case, then the ACU itself could be flaky or the signals it's getting back are in an undefined state and it's getting confused. Hard to say. A spare ACU to would be really helpful at this point. Expensive, but way easier IMO than tracking down an intermittent "somewhere" in the vehicle.

In the meantime, a couple more questions:

1) If you rotate the key OFF, then back to Accessory, does it do the unlock again?
2) Did this problem appear all of a sudden or get worse slowly over time?
3) Did it start after work was done to the car?

Keep us posted

imdvs

Thanks, Jay777. It went several days without failing then, at Cars and Coffee this morning, I left the car unlocked. When I returned to the car I turned the key to ACC no thump, but when I tried to start it, nothing, just like a dead battery but with all other functions. Went through the lock unlock with the FOB, started right up. No door locks flashing no thumping sound.

To answer your questions,
1. Next time it fails I will try that.
2. This happened suddenly.
3. Never considered that but yes, I recently removed the console to install a golden rod and SSK.

imdvs

Some additional info.
No start situation now occurs without the muffled door lock sound. I insert the key, all dash lights, fuel pump etc. come on. Remote light in clock does not go off after a period of time, car will not start. Turn key back to off without removing key then turn key to last position before start and the FOB light on clock does not go off, car will not start. No door lock lights flashing. Cycle through the lock unlock with key in ignition the FOB light in clock goes off car starts.

I've now begun to watch the FOB light in the clock, if it does not go off the car will not start.

nine9six

As stated previously, you may have a faulty/intermittent ignition switch. This would be the electro/mechanical portion Just behind the key. It looks like this.


I happen to have a new unit at a reduced price, ($70 + shipping) should you need one. I am clearing out my leftover Porsche parts...

imdvs

Thanks, nine9six, I'll let you know. Any special tools needed for removal?