I have a 1988 Bronco 5.0 EFI with the EEC-IV. I have searched by the firewall on the driver side of the engine compartment, under the dashboard at all locations, and have endlessly searched yahoo for an answer to the case of the disappearing self test pin. I have come to conclusion this thing is gone. Completely cut from the car. I will have to go to the PCM and look for it at the pin and I have never had to do anything with the PCM, but I know about the pins. Where is the PCM? What is the pin # for the self test connector? Originally my father's truck he claims to have brought it to somebody to get the codes pulled and it came up with a bad engine ground even though the ground is absolutely mint. He also says it is below the driver side instrument panel, but he's probably thinking of where an OBD-II usually is. Also if anybody has a wiring diagram for it that will be great. Thanks.