98 sohc explorer reference voltage

[smithcomm23]

I have a problem that causes the engine to rough idle, with no power, like misfiring. A code pulled out pionted to the camshaft sensor. The sensor tested good, I also verified with a replacemnet. The odd problem I'm having is the reference voltage is very low, about .3. I cut the grey/red wire at the pcm. The voltage on pcm side remains at .3, but the voltage on the wire running to all the sensors is 5.6. When I reconnect the wires it drops back to .3. Is the pcm supposed to be feeding the reference voltage? I need help please. Also the 5.6 is good at all sensors when I disconnect that grey/red wire from pcm.

 

[2000StreetRod]

CMP Sensor voltage

According to my Hayne's Repair Manual the CMP sensor on the SOHC is a magnetic pickup (variable reluctance) sensor. When a ferrous material is passed near the tip of the sensor a voltage pulse is produced. Since its common to other sensors (TPS, IAT, knock, etc) the gray/red wire that connects to Pin 91 on the PCM could be either the source or the return. I checked its resistance to ground at the TPS and it was 0 ohms so its the return. The TPS reference voltage is 5.5v. If the voltage after you cut the gray/red wire is 0.3v at the PCM and 5.6 v at the CMP sensor that's because there is no longer a path to ground. You're reading the reference voltage potential. The dk blu/org wire connected to PCM Pin 85 must be the CMP source.
According to Hayne with the ignition ON and the engine OFF and the sensor connected there should be approximately 1.5v on one of the wires to the CMP sensor. When the engine is cranked you should see a pulse increase on your voltmeter using the AC scale.