My 89 Taurus 3.0L worked like a champ until one day I went to start it and there just came a sickening vibrating noise from the starter solenoid. Upon further investigation, the car was using 4.55 Amps at all times (Off, On, Acc, Run, Start). This drain keeps the car from starting, the radio from playing, the lights, the wipers, etc etc. I traced it to the power wire going into the EEC, and spent most of a Saturday testing every wire coming out of it. There were 6 pins (not counting the power wire (pin 1)) that were using the same amperage: Pins 3, 4, 6, 16, 36 and 56. The wiring diagram says that pins 3 and 6 are for the VSS positive and negative, and pins 4, 16, 36, and 56 all go the Ignition Control Module. Specifically (from a 94 wiring diagram):
3 - Sensor Signal to Amplifier 6 - Speed Sensor Low Volt Ref to Tach Module4 - RPM Sensor Speed (Tachometer)
16 - Dedicated Ground to ICM 36 - Transmission control SW to heat module 56 - Profile Ignition pickup from the EECIf I have either components (ICM/VSS) hooked up, the ground is there, but if I disconnect them both, it goes away. So anyway, does anybody have any suggestions on what could cause two seemingly unrelated components to fail together? They seem to have nothing in common except for pin 3 and 4 being adjacent in the wiring harness. I've already checked all the wires, at the EEC, and they all test sat. Already replaced the EEC, no change. Disconnected just about everything on the engine, including the dashboard and ignition switch. About the Tachometer: I have a first gen with a mechanical cluster, with no tachometer gauge. Is there still a tachometer somewhere in the engine used for sensing or cruise control or something? maybe built into the ICM? I didn't even think about that till just now. Sensors and EEC is way out of my car-knowledge. Any suggestions are appreciated