Mechanics

PO446

2005 Cadillac Escalade

Computer problem
2005 Cadillac Escalade V8 All Wheel Drive Automatic 54000 miles

CAR CODED FOR A PO446. REPLACED VENT SOLENOID VALVE. RESET LIGHT CAME BACK ON.
CHECKED FOR POWER TO THE VENT SOL. VALVE GOOD. CHECHED FOR GROUND TO THE VALVE BY ACTIVATING THE VALVE WITH THE SCANNER, NO GROUND SIGNAL. TRACED THE GROUND WIRE BACK TO THE PCM (WHITE WIRE POS. 45)BACK PROBED AND CHECKED FOR GROUND SIGNAL AGAIN, NOTHING. BROUGH CAR TO DEALER THEY CHECK AND CAME UP WITH THE SAME THING AND REPLACED THE PCM. WHEN I PICKED UP THE CAR I ASKED IF THEY RAN A FUNCTION TEST AND THEY SAID YES AND IT PASSED. TWO DAYS LATER LIGHT CAME BACK ON. PULL THE EVAP CANISTER AND IT HAD SOME DIRT IN IT SO I REPLACED IT. RESET LIGHT BACK ON IN TWO DAYS. REPLAECED FUEL TANK PRES. SENSOR, PURGE SOLENOID VALVE.

I AM ABLE TO CLICK THE VENT SOL. VALVE WITH MY TESTER. THE LIGHT REMANS ON.I BLEW OUT THE EVAP LINES THE LIGHT REMANS ON.
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DAN T
July 6, 2010.




Can you run what's called a purge/seal function with your scanner? I recently had an H2 that had a solenoid replaced previously that ended up having a defective vent solenoid. When taken apart, the spring inside was lodged in a way to prevent the valve from venting in adequate time. If you can perform the purge/seal test, monitor the FTP data. See that it not only builds vacuum, but also releases it. There is no real way to measure the rate of time it takes to vent, but it shouldn't be noticeably slow. Almost as fast as removing the fill cap. Or if it is accessible, disconnect the hose at the vent solenoid. Compare the rate with solenoid, and disconnecting hose. When blowing through the defective solenoid by mouth, you could feel some restriction, blowing through a new one gave no restriction.
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Factoryjack
Jul 8, 2010.
THANK YOU FOR YOUR RESPONSE.I CAN NOT RUN THAT FUNCTION WITH MY TESTER. BUT I DID HAVE DOUBTS ABOUT THE FIRST VALVE THAT I REPLACED SO I DID PUT ANOTHER ONE IN.I CAN BLOW FREELY THROUGH THEM. THANK YOU AGAIN

Tiny
DAN T
Jul 9, 2010.

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