| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuits are okay. If either are defective, 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
Constant battery voltage is supplied to BATT terminal at ECM as the back-up power source. 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, the ECM will not store any other DTCs. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.