| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuits are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. |
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Mass Airflow (MAF) meter uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through MAF meter. DTC is set when ECM detects either throttle valve is fully closed and MAF meter output is more than 2.2 volts for more than 10 seconds with engine speed of 900 RPM or less, or VTA circuit signal is .63 volt or more and MAF meter output is less than 1.06 volts for more than 10 seconds with engine speed of 1500 RPM or more. Possible cause is; defective MAF meter.
Diagnostic Aids
Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.