mojorizing

With the DMM, use 20vac selection. You'll be measuring a 5 baud byte as the tool "wakes up" the ECU. Signal logic level are 0v and +12Vdc, so the value you read will be meaningless, but all you doing is checking for the presence of this preample byte on the "L" line. This is pin 15 on the OBDII connector routed to pin 7 on the round 19 pin plug for motronic, CCU, alarm, ABS. For SRS/airbag, I would expect to see a signal on pin 3 of the OBDII connector. This is for the 993.

I'm not sure if the cable you're looking for is an adapter or it's own cable.

The reason you see different number of pins is that some functions require that the engine be on, so the tool reads pulses on pin 14. If the tool doesn't offer those functions, all it needs is grnd, K, L, power. Full function tools like the hammer in addition use 14 rev counter, 19 knock output, 15 check eng. control.