P0443
 

My name is Mike my 4 door 4wd blazer Betty with 141,000 miles is throwing a p0443 code.

The P0443 code is set when the ECM detects a malfunction within the purge control valve or a short in the purge valve circuit.

I have checked fuses and wiring all looked good so I went ahead and replaced the purge valve being it was 20 years old and relatively inexpensive. Cleared codes drove and light came right back on upon shutting off and restarting vehicle. Has anyone experienced this before any thoughts or suggestions would be appreciated. Unfortunately I live in a county where emissions is required driveability is not affected. Not great with electrical curious which associated fuses would be attached to this and where to begin tracing further, is the purge valve circuit in the valve itself? I do know the pin on the plug should be grounded and pcm sends it power to open and close valve my scanner cannot operate the valve to test function. Wire is grounded.

Thanks guys I did look before I posted and didnt see much about this topic or another thread please advise.

What year is your truck?


George

Its an 01 I meant to put that initially.

The purge control valve is normally closed. The PCM energizes that solenoid periodically with ground side control to open it and draw the stored fuel vapors in the charcoal cannister into the engine intake to be burned. That solenoid has two wires. The pink wire is "hot in run or start" providing 12V via the Eng 1 fuse - 10A.. This should always measure 12V with the ignition in the run position. The PCM commands the solenoid to open by grounding the Dk grn/wht wire.

Do you have 12V on the pink wire?
Disconnect the purge solenoid and energize it to be certain that it is normally closed and opens when commanded.

If all of this checks out then there is a problem on the dk grn/wht ground side control wire or the PCM or a marginal connection on the pink power wire.

Let me know and we can go from there.


George

Thank you that is all really good information and will help me diagnose further in the morning

P0443
 

Here we go crack a cold one.

Well went out tested the ENG 1 - 10 AMP fuse which had continuity and a lit bulb on both sides of fuse with my test light and meter. Disconnected purge control valve ran a wire to a known ground and tested pink side of plug with light BOOM, bulb lit up. Stuck the positive probe from meter into plug and negative on to the ground truck was running so power fluctuated a bit but stopped at 13.84 so we are good there as well. Went to shut the truck off and to my surprise there was no CEL being displayed. Mind you i had ran errands earlier this morning and the light was on i never cleared the codes or disconnected the battery. Figured i would shut the truck off and the CEL would come right back on but it didn't. Haven't driven it yet to see what happens next. My guess is the plug wasn't seated all the way or possibly knocked some junk off poking around the terminals which looked clean with no corrosion originally. Who knows to my knowledge disconnecting and reconnecting something would have no ability to clear or fool the computer enough to shut the light off. Time will tell so the cold one is hopefully for a celebration or atleast the start to a buzz for when it comes on again.

Thanks Again George for your help, to you and anyone else if you have any explanation, comments or something I missed im all ears.

Time will tell fingers are crossed.

A couple of points.

the pink power wire needs to be capable of maintaining 12v under the load of the solenoid so connect the pink power wire to the solenoid but with the ground side control disconnected and then provide a solid ground to the other side of the solenoid and measure the pink wire voltage.

unfortunately the ground side control cannot be checked unless the solenoid can be commanded. That said be careful with loading the pcm control to make sure that you don’t fry your pcm.

Lastly make sure that your solenoid is opening and closing with direct power/no power.




George