fob programming/Emergency start debug
If you're unable to program your FOBs, don’t rush out and buy a new immobilizer or send it off for programming— there might be a simple DIY fix.
The immobilizer relies on two signals for programming: KEY and IGN, which come from the ignition/lock assembly, as shown. (For 1995 models, the IGN signal also passes through the Airbag Control Unit.) During programming, you enter the 4-digit PIN code by turning the key ON and OFF following feedback from the immobilizer warning light. Both of these switches need to be functioning properly or the procedure will fail.
FOB programming system in 1995 North American 993's:
FOB programming system in 1996-98 North American 993's:
During the programming procedure, the immobilizer expects the KEY switch to close after Step 2 and remain closed until the process is complete. If the switch opens, even briefly, the warning light won’t flash after Step 3, and the procedure will abort. Fortunately, there are a few work-arounds you can try. The "quick and dirty" fix is to temporarily bypass the KEY switch by wiring 12V to it. This makes the immobilizer think the switch is functioning properly, allowing programming to continue. getting to the switch can be difficult, but on North American 993 models, you can access the same point at gong relay pin 85:
In North American 993 models, the gong relay is located behind the fuel gauge. To access it, remove the gauge and unplug the tall relay. Wrap a piece of wire around terminal 85 and plug the relay back in. When you retry the programming procedure, connect 12V to this wire before you turn the key ON at the start of the process. If the warning lamp flashes after Step 3, finish the procedure, then remove the jumper. Do not leave the switch bypassed.
If you have an IMMO BLOCK installed in the gong socket, you can attach the 12v bypass wire to this pin:
You can also replace the KEY switch (part number 911-613-125-00). Keep in mind, though, the issue may not be the switch but the mechanism that activates it. If that’s the case, you’ll need to replace the whole assembly (part number 964-347-917-01 or 00). Given that most owners rarely need to program a FOB, the temporary bypass might be the way to go.
Less commonly, a faulty IGN signal can cause problems. In this case, the immobilizer enters programming mode, ok (indicated by the immobilizer warning light flashing after Step 3), but receives a corrupted PIN code. If this happens after repeated attempts, the ignition switch assembly needs to be replaced (part number 964-613-012-00).
