2005 PCM Replacement

[muddydan]

2005 Ford Explorer 4 DR XLT MPV 4X4
4.0L SOHC 5R55S Automatic

About 2 months ago my ex had a bad burning smell after a run in with some ice. It came up with two codes

:thumbdwn0720 Output Shaft Speed (OSS) Sensor Circuit
:thumbdwn0722 Output Shaft Speed (OSS) Sensor Circuit No Signal

:thumbdwn:Slips in M1, M2, D. Reverse and 3rd gear work(I was told this is FMEM mode)

We ruled all internal transmission problems. I went through the entire transmission wiring harness(7C078) which has PCM 175-t connector at one end. All wires in the entire harness, including connectors, ohmed within suggested resistance. *most were .3ohms or less* The sensor was switched with a new sensor and also placed in position of the ISS and TSS to verify working condition, sensors are fine. We also went through a diagnose by symptom and TJ pinpoint test on Ford tech service. PID test also shows OSS(RPMS) reading when vehicle is in gear with brakes applied.

All I can think of is that the PCM needs to be replaced. Maybe the computer read to much resistance in the circuit and may have fried a processor in the PCM? Any input would be helpful

 

[jah81592]

If you have a spare vehicle you could ship the processor to a specialist which could test it.

 

[High_Order1]

well....

you have to be very careful when diagnosing this particular system. A high impedance VOM is a must. You can actually cause damage backprobing because of the sensitivity of the car to variations in voltage.

It sounds like you followed the pinpoint diagnosis chart. UNLESS, the reactor ring or everwhat they call the magnety thing that rotates in there has failed. That could also throw those codes. You coul use a storage oscilliscope to look at the pulses as the shaft rotates....

you could also have a bent pin, or short at the pcm end of the plug, right?

Shawn