Vehicle: 1997 Ford Explorer, 4WD, V6-245 4.0L SOHC VIN E, EFI, Automatic Transmission/Transaxle

Mileage: 195,833 miles

Problem: This vehicle failed smog inspection, and the malfunction indicator light (MIL) was on.

Case Details: The technician connected a scan tool and found diagnostic trouble code: P0443 Evaporative Purge Valve Circuit. He inspected the purge valve and saw that battery acid was leaking on it. He checked the wiring harness and connector. They were OK, and there was battery voltage and ground present at the harness.

When he received the new purge valve from the dealer, the technician checked the resistance, which was found to be within specifications. He installed the new valve and reset the MIL. During the 10-mile-long test drive, the MIL came back on. The technician connected a test light to the purge valve connectors to see if the electrical harness was in good shape. With his scan tool, he could turn the valve on and off, and the light bulb turned on and off as well. The purge valve passed a vacuum test as well.

It was time to call ALLDATA Tech-Assist for some diagnostic advice.

The consultant recommended connecting the light bulb again, commanding the valve on, then wiggling the harness to see if the light flickers or gets dim. If so, then there is a harness or connector issue. If the light did not flicker or dim, then he advised checking the amperage draw of the purge valve with it commanded on. The amperage draw should read 0.3 to 0.4amps. If that reading falls within specifications, then the PCM may have an internal problem. The consultant said that he has seen several PCM replacements because of the DTC found earlier.

Confirmed Repair: The technician performed the tests as advised and the test results fell within specifications. He installed a new PCM and went on a good test drive. No more MIL, the engine ran great, and it passed the smog inspection. Problem solved!