fob programming/Emergency start debug
If you can't program FOBs, don't rush out to buy a new immobilizer or send it off to be programmed - there may be a simple DIY solution.
The immobilizer uses two signals to program FOBs: KEY and IGN. These originate at the ignition/lock assembly and routed to the immobilizer as shown below. (The only difference between 95's and later years is that in 95's the IGN signal passes through the Airbag Control Unit). During programming, the user enters the 4-digit PIN code by rotating the ignition key ON and OFF, guided by feedback from the immobilizer warning light.
While problems can occur anywhere in the KEY or IGN signal paths, the most common problem is a faulty/intermittent KEY contact switch.
FOB programming system in 1995 North American 993's:
FOB programming system in 1996-98 North American 993's:
The immobilizer expects the KEY switch to close after Step 2 in the programming procedure and stay closed until the procedure is complete. If it opens at any time, even momemtarily, the warning light will fail to flash after Step 3 and the process will terminate.
Fortunately there are some DIY workarounds to try. The "quick and dirty" approach is to simply bypass the KEY switch by temporarily wiring 12v to it as shown. The immobilizer will then think the KEY switch is good and programming can continue. It's tricky to get to the switch but in North American 993's 12v can be wired to gong relay pin 85:
In North American 993's the gong relay is behind the fuel gauge. Pop the gauge out and unplug the tall relay. Wrap a piece of wire around terminal 85 and plug it back in. Try the procedure again, this time connecting 12v to the wire at the same time you turn the key ON at the start of the procedure. If the warning lamp flashes after Step 3, complete the procedure then remove the jumper. Do not leave the KEY switch bypassed.
If you have an IMMO BLOCK installed in the gong socket, you can attach the 12v bypass wire to this pin:
For a more permanent fix replace the KEY switch (P/N is 911-613-125-00). Be aware, though, that the problem may not be the switch - it could be the mechanism actuating the switch. If that's the case, the entire ignition assembly (P/N 964-347-917-01 or 00) will need to be replaced. For the few times most owners will ever need to program a FOB, the switch bypass may be the best solution.
Less commonly, a faulty IGN signal will cause a problem. In this situation, the immobilizer enters programming mode ok (indicated by a flashing immobilizer warning light after step 3), but the PIN code gets entered in error. The indication that this is the problem is that the door LED doesn't flash after the PIN code is entered. (Entering the worng PIN code for the immobilizer does the same thing). If this happens, the ignition switch contact assembly may need replacement (P/N 964-613-012-00).
© 2019 PCAR Products. All rights reserved.