I realize this forum is virtually dead but I am hoping there are still a fewe Ford Experts still monitoring.
I have a 1996 Ford Ranger 4.0 5 speed longbox standard cab 2 wheel drive truck with no power windows. mirrors or locks. The speedometer has recently stopped working and I have found something that does NOT make any sense. with the ecu plug connected or disconnected and the engine-cab connector connected I get a DC voltage reading of about 8.5 volts with the key off, rising to 12 volts with the engine running, and at the same time an AC voltage - cannot remember the base when not running, but rizing to 15+ volts with the engine running. When I disconnect the harness to the cab the voltage goes away. The speed censor gives me about 2.6 volts AC when spun by my Milwaukee battery drill and the signal can be read between pins 33 and 58 on the ecu - either connected or disconnected - as long as the cab harness is disconnected In the wiring diagrams the only thing these wires connect to in the cab are the speedo and the CTM / GEM. It would also connect to the speed controller amplifier/servo assembly if the truck had cruise control (which it does not) Pulling every fuse, one at a time, from the fuse panel in the end of the dash panel does NOT kill either the AC or DC voltage across the speed sensor. Is there any function or misfunction of the CTM/GEM on this vehicle that could/would feed either an AC oe DC voltave bact to the ECU/speed sensor circuit????