"I am now having no luck programming another fob (to replace the one I laundered) for my car and it is not the alarm system causing the problem. I have not taken the time to work through it yet but I suspect it is an intermittent switch in the ignition key mechanism. There is a switch in the locking mechanism that senses the key is inserted, turns on the bong when you open the door and have the key in the ignition. The output of that switch goes to the immobilizer control unit also. If it is not working or is intermittent it will not allow the immobilizer to be programmed."

That's a common problem as the 993 gets older.

 

Andy, I had heard/read that before. Was it your post? I was unable to verify if the difference in resistence between the LED and filiment bulbs was valid. Have you confirmed this to be true?

Thanks loads,
Paul[/QUOTE]
Hi paul,
My understanding of basic electronics is that an LED is a Light Emitting Diode. A diode is a semiconductor device that passes current in only one direction. so it may look like a switch in certain circuits. How it may interact with a computer controlled circuit seems like it may influence how the current flows and what the computer recognizes as problematic.
On the other hand if the door LED is not flashing in couplets there probably is no issue with a system. However I have never tried this.
PS no this is my first post bringing up the LED issue.

Andy

 

In my car I have added some aftermarket features such as automatic door locking ten seconds after the ignition is turned and a headlights/ turn signal lights left on with ignition off buzzer. If the car you have has any aftermarket stuff like this it may be the cause of the problem. In my case I will need to disconnect one or both of these features any time I wish to program keys in the future.
Andy

 

So I reinstalled the engine bay light harness and tried the procedure again. There is still no Alarm light blinking going on in Step 2. The alarm arms fine, the door LEDs blink once upon locking and unlocking, but it won't allow me to enter programming mode...

 

Ilko,
I had also heard from a very reliable source, that the relay located just behind the steering wheel, in the trunk, will affect the operation of the immobilizer...FWIW
Just passing along the info, regardless of the validity.

 

"How it may interact with a computer controlled circuit seems like it may influence how the current flows and what the computer recognizes as problematic."

Using a LED for the immobilizer indicator will not affect the function/operation
of the immobilizer. That indicator is only used for the remote programming
operation. As mentioned, the ignition switch and the buzzer switch must
function perfectly or the programming operation will fail.

"There is still no Alarm light blinking going on in Step 2."

Then:

1. The code is incorrect, or
2. the ignition switch is bad, or
3. the buzzer switch is bad, or
4. the programming sequence wasn't followed to the letter, or
5. the immobilizer ECU is bad.

If possibly '5', then try programming in another known good 993.

 

Loren,
Could Andy have been referring to the resistance in the circuit for the glove box, trunk, engine bay, interior lights; if LED's were installed in those locations and not necessarily an LED used for the immobilizer indicator?

P.S. I love this thread and the information being exchanged!

 

"Could Andy have been referring to the resistance in the circuit for the glove box, trunk, engine bay, interior lights; if LED's were installed in those locations and not necessarily an LED used for the immobilizer indicator?"

Not really, as all contacts used for detection don't measure current and just
'look' for a ground (~ zero volts).

 

Thanks a bunch Loren! Your response was my understanding, but someone suggested that the computer checks for resistance when executing the self diagnostics.

Unfortunately, I admittedly do not know enough about the system software logic, or the diagnostic functions it checks for the ready state feedback

 

Appreciate everyone's comments on my original posting, since I need to take the car to the dealer for some other issues, guess I will let them program the FOB since I don't have any more hair to lose!!!!!!

 

Just wanted to let you know, I once replaced the ignition switch on the back of the ignition lock on my 86' Carrera. The 993 looks to be of the same design, it's not a big job.

 

"Just wanted to let you know, I once replaced the ignition switch on the back of the ignition lock on my 86' Carrera. The 993 looks to be of the same design, it's not a big job."

Actually, replacing the 993 ignition is much more difficult.

 

I only have one working key so I bought a second from Suncoast.

The door sill light double flashes so I get to step 1 of the programming and the warning light in the clock goes on but does not turn off. I have the suncoast porsche LEDs in the interior lights and under hood and have the Tore LED kit for the exterior lights. My battery is charged to 79% according to my charger. The owners manual has a different procedure than the PDF published in this thread. The owners manual says use the key to unlock/lock/unlock, turn ignition key to on, then follows the PDF process. When I tried the owner manual process the warning light in the clock doesn't turn on and eventually the alarm goes off.

Any recommendations? I'd not want to deinstall all of the LEDs. 96 C4S. Is it easier to disable the immobilizer?

 

schroed911,

See hoggle's post #12

P.S. It is not easier to bypass the immobilizer, and it will be more costly than removing LED's

 

While I think the 3.2's and 3.6's share the same P/N for the back of the ignition switch, as Loren states, the replacement effort is not the same.

I remember pulling the whole ignition and steering lock assembly using the proceedure in the stupid book, 101 Things to do to your Porsche. Finally found a set screw/locking nut, holding the steering lock portion in place. not a word of this in the book, and you are definitely working by feel rather than sight, for most of the project.
BTW, Pulling the drivers seat is a must, if you value your back!