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

[NJayL]

Hello everyone. I was hoping someone could chime in and impart some advice about what else to check on my Explorer. I've had a P0403 and P0443 for the last 4 months.

1. When both codes first threw, I checked the evap purge valve, found it was bad, and replaced it.
2. Codes remained, so I replaced the EGR valve. I was getting ready for a cross-country move and didn't have time to do an in-depth diagnosis.
3. Had to execute military orders across the country and drove from VA to CA. No issues whatsoever. Truck ran great and gas mileage was in the twenties, but codes remained.
4. Replaced the PCV valve.
5. Checked the ground and power to purge valve and EGR, no issues.
6. Checked wiring to purge valve and EGR and did not find any broken wires or chaffing.
7. Removed the PCM and sent to SIA Electronics. They tested it and found nothing wrong.
8. Cleaned PCM wire-harness connectors with water and Dawn soap and let dry for a few days.
9. Codes returned within a day.

I'm stumped. I don't know what else it could be. Maybe the PCM is still bad and SIA misdiagnosed? I really, really don't want to bring the car in to a shop or dealership.
Any advice would be greatly appreciated!

 

[NJayL]

I thought I would update my original thread.

I took the vehicle in to a trust shop near me and this is what they tested:

• Checked circuits between EGR module, fuse 42 and PCM connecter pins 21, 57, 62, and 63.
• Checked circuits between EGR purge solenoid, fuse 42 and PCM connector pin 6.
• "Wiggle tested" engine harness while testing each circuit.
• All circuits have specified continuity, power, ground, and VREF.
• Confirmed test of function for component EGR and evap purge valve.
• Checked vacuum for leaks of EGR system, no leaks found.
• Cleared all codes and reset KAM (Keep Alive Memory).

The codes returned one day after getting it back from the shop. Next steps are to contact Ford and see if they have a software update for the PCM, and if not or it doesn't work, time to shop for an aftermarket or remanufactured PCM. FYSA Ford has a "unknown in length" backorder on PCMs for this vehicle.

 

[Bazz270]

Take your harness apart and start to check for visual damage.

Wiggle test...funny...there is 1000 reason for damaged harness to pass pin point test.

Without any evidence of inner PCM damage or corrosion you have nothing to do with reman PCM swap.

The only way for PCM can be related to EVAP bad connection codes its a visual damage,board corrosion or bent PCM side pins.

In my opinion...

Reman electronics usually it is a piece of junk.even ford or motorcraft.they are possibly use some shady subcontractors with Ford equipment and checklists

 

[NJayL]

Take your harness apart and start to check for visual damage.

Wiggle test...funny...there is 1000 reason for damaged harness to pass pin point test.

Without any evidence of inner PCM damage or corrosion you have nothing to do with reman PCM swap.

The only way for PCM can be related to EVAP bad connection codes its a visual damage,board corrosion or bent PCM side pins.

In my opinion...

Reman electronics usually it is a piece of junk.even ford or motorcraft.they are possibly use some shady subcontractors with Ford equipment and checklists

Bazz270, can I take my truck to you for diagnosing lol? I trying to understand how taking apart the wiring harness would help, since all the continuity for all the pertinent connections has already been confirmed...

The PCM looks great, almost like new. Ford has a 2-year backorder on new PCMs, and even the local dealership parts counter said they are now using OReillys or Automotive Technologies in Houston.

Thanks for taking the time to respond to my post!

 

[Bazz270]

Engine vibration could cause intermediate harness shortcuts.several vehicle modules and wiring circuits starts to operate after one or more warm cycles.

I mean that steady state static resistance check means almost nothing for complicated electric malfunctions during engine vibrations.

 

[NJayL]

Engine vibration could cause intermediate harness shortcuts.several vehicle modules and wiring circuits starts to operate after one or more warm cycles.

I mean that steady state static resistance check means almost nothing for complicated electric malfunctions during engine vibrations.

Ah, got it. That makes a lot of sense! Thank you for the suggestion!

 

[TomacRitchey]

Hi, I know this is an old thread but were you able to solve this problem? I have the same codes right now. Thanks and keep safe everyone!

 

[DSHEP63D]

Hell

Hi, I know this is an old thread but were you able to solve this problem? I have the same codes right now. Thanks and keep safe everyone!

It may be an older thread but with the car market the way it is my ole Exploder has got to last me just a few more years… Having the same issue right now. Found this on another thread
(Found a strange cause for the P0403, P0443 codes | Ford Explorer - Ford Ranger Forums - Serious Explorations

https://www.explorerforum.com/forum...for-the-p0403-p0443-codes.464373/post-3635946

Will be doing this to see if it resolves some issues. It makes sense and I have seen this done on some other German cars. With this having that wonderful SOHC boat anchor in it I can see this being a plausible scenario. Only time and beer will tell…

 

[Sambosat]

Hell

It may be an older thread but with the car market the way it is my ole Exploder has got to last me just a few more years… Having the same issue right now. Found this on another thread
(Found a strange cause for the P0403, P0443 codes | Ford Explorer - Ford Ranger Forums - Serious Explorations

https://www.explorerforum.com/forum...for-the-p0403-p0443-codes.464373/post-3635946

Will be doing this to see if it resolves some issues. It makes sense and I have seen this done on some other German cars. With this having that wonderful SOHC boat anchor in it I can see this being a plausible scenario. Only time and beer will tell…

Link is not working

 

[GB1977]

Any update on this thread? Did it work for you? i now have the same two codes.

 

[jbwilli]

REF 2009 EXP 4.0L: Ditto! Exact same issues on my 2009 for 3 months. Removed and replaced with new oem EGR (my has solendoid on top), Purge valve (passes bench), Canister vent valve (@ right axle/tank area), Vacuum line to purge valve, vacuum lines to EGR and under intake and removed intake, cleaned and replaced intake gaskets. Same result as yours! I would love to see any updates on the end result of this OLD, but valuable string. FYI: These model have electrical connectors that are known to have wire insulation at the last 1/8 inch to the connectors crack and break off! I had to repair 2 previously! Last night I found the 2 wires to the vapor purge valve in this condition and they were lightly touching each other! Be advised, you cannot see these bare wires at the connectors unless you peel back the electrical tape and spiral wrap AT THE CONNECTOR. I will update IF this cures my CE light. I hope this thread will be updated with the final outcome of the original poster OR the link that doesn't work. GOOD LUCK ALL!

 

[GB1977]

REF 2009 EXP 4.0L: Ditto! Exact same issues on my 2009 for 3 months. Removed and replaced with new oem EGR (my has solendoid on top), Purge valve (passes bench), Canister vent valve (@ right axle/tank area), Vacuum line to purge valve, vacuum lines to EGR and under intake and removed intake, cleaned and replaced intake gaskets. Same result as yours! I would love to see any updates on the end result of this OLD, but valuable string. FYI: These model have electrical connectors that are known to have wire insulation at the last 1/8 inch to the connectors crack and break off! I had to repair 2 previously! Last night I found the 2 wires to the vapor purge valve in this condition and they were lightly touching each other! Be advised, you cannot see these bare wires at the connectors unless you peel back the electrical tape and spiral wrap AT THE CONNECTOR. I will update IF this cures my CE light. I hope this thread will be updated with the final outcome of the original poster OR the link that doesn't work. GOOD LUCK ALL!

Nice work! Thank you for taking the time to post this. Let us know if it fixes your issues. I’m really tempted to pull as much of the harness as I can off the car and fix replace whatever I find.

 

[jbwilli]

Sad to say, I carefully separated the wires at the connector and applied a quality 'liquid electrical tape' to those tiny bare sections. Only 2 wires, 1 green and 1 yellow. Cleared codes and CE back on 10 miles later. I will attempt to attach a pic of this connector to show how the insulation breaks away. No, it is not a rodent issue. I have seen this too many times on this era Explorers (poor quality wire insulation). I need to see the wiring diagram for this 2 wired Fuel Vapor Purge Solenoid for 2009 Ford Exp EB 4.0L V6 and trace them all the way to the PCM. I suspect I am getting no signal voltage to the solenoid from the PCM? Both the old removed unit and the new installed OEM Ford unit, open and close properly on a 12V bench test, but I feel no vacuum on the bottom port that routes to the fuel canister when the unit is installed with engine running. How do you check the signal voltage with a meter (back probe each wire (1 yellow1 green) 1 at a time to ground OR between each other? What should the voltage be? Should it be steady of vary with engine conditions. I would appreciate any info on this subject. Until then, I wil hunt for how to test this circuit and a wiring diagram of it. THANKS ALL!

 

[GB1977]

Sad to say, I carefully separated the wires at the connector and applied a quality 'liquid electrical tape' to those tiny bare sections. Only 2 wires, 1 green and 1 yellow. Cleared codes and CE back on 10 miles later. I will attempt to attach a pic of this connector to show how the insulation breaks away. No, it is not a rodent issue. I have seen this too many times on this era Explorers (poor quality wire insulation). I need to see the wiring diagram for this 2 wired Fuel Vapor Purge Solenoid for 2009 Ford Exp EB 4.0L V6 and trace them all the way to the PCM. I suspect I am getting no signal voltage to the solenoid from the PCM? Both the old removed unit and the new installed OEM Ford unit, open and close properly on a 12V bench test, but I feel no vacuum on the bottom port that routes to the fuel canister when the unit is installed with engine running. How do you check the signal voltage with a meter (back probe each wire (1 yellow1 green) 1 at a time to ground OR between each other? What should the voltage be? Should it be steady of vary with engine conditions. I would appreciate any info on this subject. Until then, I wil hunt for how to test this circuit and a wiring diagram of it. THANKS ALL!View attachment 452696

There is another thread on here somewhere that shows the wiring diagram. Just an FYI - Never backprobe between the two. That is essentially placing a jumper wire in the circuit, without a load and risks blowing the PCM.

 

[GB1977]

There is another thread on here somewhere that shows the wiring diagram. Just an FYI - Never backprobe between the two. That is essentially placing a jumper wire in the circuit, without a load and risks blowing the PCM.

The PCM supplies the ground and is the switch for this circuit. On what I said above, you could do it with a test light or a DVOM, because they are a load in themselves, but if the two back probes touch, bye bye puter.

 

[jbwilli]

The PCM supplies the ground and is the switch for this circuit. On what I said above, you could do it with a test light or a DVOM, because they are a load in themselves, but if the two back probes touch, bye bye puter.

Thanks much for the rapid reply! Yes, I was extremely careful when using my 'fused' DVOM to read the DC volts between the green and yellow at the connector terminals, with key on and key off. Key off was 0 dcv and Key on was 12.4 dcv (same as batt voltage). I plugged the connector back to both the old and the new solenoids with key off. Turned key ON and no CLICK...nothing. Ran jumper from battery + -, to both solenoids in my hand and both open and close with a positive click. Checked ALL fuses in the engine compartment fuse box and ALL good! I did not take any 'back probed' readings from yellow to ground or green to ground with the connector installed and the engine running. Should I? What results should each wire display? Remember, with a good solenoid installed and the engine running, there is a good vacuum from the intake line to the solenoid, but NO vacuum at the solenoid outlet port to the line going to the fuel vapor canister! I do believe I am getting close to discovering the fault, but without a wiring diagram or signal voltage info, I remain lost. I found wiring diagram in this forum for the TPS connector to PCM, but have yet to find same info for the Canister Purge Solenoid connector.

 

[GB1977]

One thing -

"I was extremely careful when using my 'fused' DVOM to read the DC volts between the green and yellow at the connector terminals, with key on and key off. Key off was 0 dcv and Key on was 12.4 dcv (same as batt voltage). "

Can you clarify you were reading both terminals at the same time?

If you were, there is a difference between how your car is acting versus mine. For me, I had to use Bi-Directional control in Forscan to turn on this solenoid (which ordered the PCM to supply the ground). It was not on when Key was on. If mine is behaving the way it was intended (I need to research this), then maybe you have a short to ground in your ground wire?

 

[GB1977]

One thing -

"I was extremely careful when using my 'fused' DVOM to read the DC volts between the green and yellow at the connector terminals, with key on and key off. Key off was 0 dcv and Key on was 12.4 dcv (same as batt voltage). "

Can you clarify you were reading both terminals at the same time?

If you were, there is a difference between how your car is acting versus mine. For me, I had to use Bi-Directional control in Forscan to turn on this solenoid (which ordered the PCM to supply the ground). It was not on when Key was on. If mine is behaving the way it was intended (I need to research this), then maybe you have a short to ground in your ground wire?

Here is the video I was referencing when I did my test.

I'm not as confident as this guy though. I want to do further visual inspection and testing before blaming the PCM. Mine is running and driving great, so I do suspect it is the PCM (working but not realizing it's working)

 

[jbwilli]

One thing -

"I was extremely careful when using my 'fused' DVOM to read the DC volts between the green and yellow at the connector terminals, with key on and key off. Key off was 0 dcv and Key on was 12.4 dcv (same as batt voltage). "

Can you clarify you were reading both terminals at the same time?

If you were, there is a difference between how your car is acting versus mine. For me, I had to use Bi-Directional control in Forscan to turn on this solenoid (which ordered the PCM to supply the ground). It was not on when Key was on. If mine is behaving the way it was intended (I need to research this), then maybe you have a short to ground in your ground wire?

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!

 

[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!

FYI - I found this on an expedition forum.

Free Service Manuals for Ford Truck vehicles | Operation CHARM

Detailed repair/service/workshop manuals for almost all Ford Truck vehicles, including electrical diagrams, recommended bolt torques, and estimated labor times.

charm.li

It's all the pin point tests for our explorers. Hope it helps. I'm going to check mine this weekend.