| CAUTION | If ECM replacement is instructed in following tests, always ensure ECM connectors and ground circuit 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
Battery voltage is supplied to ECM BATT terminal (constant). DTC is set when open in back-up power source is detected. Possible causes are
- Back-up power source circuit is open.
- Defective ECM.