Mystery codes 0403 and 0443 - 2010 Ford Explorer XLT 4.0L

[GB1977]

Yes, I read the dcv between the green and yellow wires in the disconnected connector end, with engine not running but with key on. Used my fused DVOM. The mystery is, with 12.4 vdc reading at the connector, why doesn't the solenoid 'click' to open when I connect it? (the obvious answer is, it is not making a circuit to ground??? If I connect the batt (12.4 vdc) to the solenoid connections with it in my hand, it clicks to open every time! I agree, one of the wires must be shorted to ground BEFORE it makes continuity back to the PCM's ground circuit/switch! Which wire is the signal TO the solenoid from the PCM and which wire is the true ground wire back to the PCM? I will go check each wire with KEY OFF for continuity to ground and/or short to each other. I see several yellow and green wires going to more than one of my 3 PCM huge multi wire connectors at the PCM! Seems I should disconnect all 3 of these connections to the PCM and find the yellow and green wires that are common to the yellow and green wires at the solenoid??? I may opt to do noting until I talk with my local emissions mechanic who got it to pass emission last February for 1 day before the CE came back on with P0401 and PO455 codes!

Did you learn anything new about this? I spent some time this weekend on it. My explorer doesn’t appear to have any wiring issues. The split loom is brittle in places, but all the insulation is intact. I checked for a short to ground in the purge valve control wire, but the computer seems to be controlling it fine. I believe mine is the pcm after all.

 

[jbwilli]

Did you learn anything new about this? I spent some time this weekend on it. My explorer doesn’t appear to have any wiring issues. The split loom is brittle in places, but all the insulation is intact. I checked for a short to ground in the purge valve control wire, but the computer seems to be controlling it fine. I believe mine is the pcm after all.

I did some more checks on Green and Yellow wires at the connector to the Purge Solenoid Valve.
Key Off: Continuity of each wire thru the connector is good. Green wire is common to grd. Yellow is not.
Key On/Engine Off: Volts: Green to grnd = 12.3 Volts (bat voltage). Yellow to grnd = .45mVolts.
Key On/Engine Running: Green to grnd = 14.7 Volts (bat voltage). Yellow to grnd = 14.7 volts.
Solenoid remains closed (no vacuum @ port to cannister line to fuel talk cannister).
Bench check of purge solenoid = fully open with 12V applied, fully closes with no voltage.

I too fear PCM may be at fault or green/yellow wiring to and from it. PCM trip to SIA may be in order.
I really need to know what the voltage values at Green and Yellow are supposed to be.

 

[GB1977]

Key On/Engine Running: Green to grnd = 14.7 Volts (bat voltage). Yellow to grnd = 14.7 volts.

are you backprobing the yellow wire while the solenoid is connected? If so, this make sense. If the solenoid was disconnected and you front probed the yellow/brown wire, then it seems you have a short to power on this somewhere. That wire is the ground from the computer to close the circuit. Shouldn't have anything on it (no power/no ground) until the computer wants to open the solenoid, then it would close the ground to complete the circuit.

 

[jbwilli]

are you backprobing the yellow wire while the solenoid is connected? If so, this make sense. If the solenoid was disconnected and you front probed the yellow/brown wire, then it seems you have a short to power on this somewhere. That wire is the ground from the computer to close the circuit. Shouldn't have anything on it (no power/no ground) until the computer wants to open the solenoid, then it would close the ground to complete the circuit.

Yes, all voltage back probing was with the connector installed onto the installed purge valve solenoid.
Each wire checked individually from wire to batt ground.
Took 2 readings. one with KEY ON only (engine not running) and another with KEY ON (engine running).
Note that the green wire reads same as battery voltage both times.
The Yellow wire had little to no voltage with KEY ON only, but was equal to batt voltage KEY ON/engine running.

I will try and trace the yellow wire to its pin # location on the PCM. I will disconnect at solenoid end and the PCM end and check continuity check thru the full length of the yellow wire in the harness I assume it should read good continuity thru itself, AND NOT be common to ground when disconnected at both ends. I assume the pin at the PCM it connects to should also NOT be common to ground with KEY OFF. More to come in a few days! Thanks for your input!