Pin 3 is the 12v power on the 38 pin connector, not the 16 pin. On the 16 pin connector, which you have on the 94 E320, the red plug goes into socket 16. The most important sockets are 8 and 14, and of course the built in LED light. HFM is short for hot film mass air flow sensor. SFI is sequential fuel injection. EA is electronic accelerator. You're not going to hurt anything.