| 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
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 an open or short in MAF meter circuit for more than 3 seconds with engine speed at 3000 RPM or less. ECM will operate in fail-safe mode if DTC P0100 is set. Possible causes are
- MAF meter circuit is open or shorted.
- Defective MAF meter.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0100, use scan tool to access CURRENT DATA to confirm mass airflow meter air flow rate. If ratio is 0.0 gm/sec., VG circuit may be open or shorted, or power source circuit may be open. If ratio is 271.0 gm/sec. or more, EVG circuit may be open. Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.