| 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 article in GENERAL INFORMATION. |
Circuit Description
ECM receives operating condition (on/off) of A/C system from A/C ECU and also receives electrical load information from the body ECU. ECM uses this information to control engine (idle up, etc.). DTC will set if there is no communication to body ECU or A/C ECU from 5 seconds or more. Possible causes are
- Faulty body ECU.
- Faulty A/C ECU.
- Communication network fault.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.