Note. For information on engine immobilizer system, see COMPUTERIZED ENGINE CONTROLS in THEORY & OPERATION article.
| 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 - LEXUS article. |
Circuit Description
The ECM receives the operating condition signal (ON/OFF) of the A/C from the A/C ECU, and it also receives the electrical load information from the gateway ECU. The ECM uses this information to control the engine. DTC will set if no communication from body ECU and A/C ECU is detected by ECM for 10 seconds or more. Possible causes are
- Faulty gateway ECU.
- Faulty A/C ECU.
- Faulty communication bus.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.