Yet Another P0443 Thread

[Rut Row]

I'm basically looking for confirmation before I send the PCM in to @Wranglerfix for repair.

After changing the fuel pump, a few days later I started getting the dreaded P0443 code. I read all the threads here and watched the recommended YT video on testing the EVAP/Purge Control solenoid.

Electrically the wiring to the solenoid is good. I get power to it and the wire back to the PCM is good. But when the engine is warm there is no trigger from the PCM.

The solenoid is not stuck open. I don't get vacuum at the tank side when running and the plug disconnected.

It appears that the PCM is bad.

Have I missed something? What else should I test/check?

I've read that if not fixed, this could lead to problems down the road but not immediately. Correct?

 

[macleanflood]

Is it possible one of the other sensors is shorted to ground?

But then you wouldn't have 5v.

PCM is just providing ground to complete the circuit.

@Wranglerfix might have more suggestions.

-Mac

 

[Wranglerfix]

What year is your Jeep?

 

[macleanflood]

What year is your Jeep?

According to his profile it's 2003...

-Mac

 

[Rut Row]

What year is your Jeep?

2003

 

[Rut Row]

Is it possible one of the other sensors is shorted to ground?

But then you wouldn't have 5v.

PCM is just providing ground to complete the circuit.

@Wranglerfix might have more suggestions.

-Mac

agree - that isn't happening - no ground from the PCM.

 

[ItchyDong]

Can you command it open with a scan tool?

Can you force it open by giving it a ground and watching your fuel trims rise?

 

[Rut Row]

Can you command it open with a scan tool?

Can you force it open by giving it a ground and watching your fuel trims rise?

I don't have a scan tool. But if I ground it, the solenoid should open and vibrate. I'll try that - thanks!

 

[Feralkid]

Did you check the large connectors of the wiring harness that are on the fire wall? It can't hurt to unplug and inspect them for corrosion and moisture. I would also check the PCM connectors for corrosion. Corrosion on the connector pins is far more likely than anything else on a 22 year old vehicle.

 

[ItchyDong]

I don't have a scan tool. But if I ground it, the solenoid should open and vibrate. I'll try that - thanks!

I misspoke yesterday. I was tired. The only way to verify it’s truly working and opening is with a scan tool and live data. Your upstream O2 O2 sensor should see a sharp rise in voltage when you give it a ground and you should see fuel trims go negative in an attempt to take away fuel.

A solenoid that clicks does not prove that anything inside is functioning as designed. Only data will confirm or deny.

 

[Rut Row]

Did you check the large connectors of the wiring harness that are on the fire wall? It can't hurt to unplug and inspect them for corrosion and moisture. I would also check the PCM connectors for corrosion. Corrosion on the connector pins is far more likely than anything else on a 22 year old vehicle.

I disconnected C3 so I could test continuity to the solenoid.