| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
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.
Diagnostic Aids
If DTC P1600 exists, ECM will not store any other DTCs. Using scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.