System Operation
NOTE:
For information on engine immobilizer, see THEORY & OPERATION
article.
CAUTION:
If ECM replacement is instructed during any test procedures, 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 in GENERAL INFORMATION.
- Ensure engine is at normal operating temperature. Ensure idle speed is 650-750 RPM. Ensure transmission is in Neutral. Turn A/C off. Connect Fused Jumper Wire (09843-18020) between terminals TE1 and E1 of DLC No. 1. See Fig 1. On ES300, DLC No. 1 is located on front of air intake chamber. On RX300, DLC No. 1 is located on left side of engine compartment, behind fuse box.
- On all models, engine speed should increase to about 1000 RPM for about 5 seconds then return to idle (650-750 RPM). If engine speed is as specified, go to AIR ASSIST SYSTEM . If engine speed is not as specified, disconnect jumper wire from DLC No. 1. Check IAC valve operation. See IAC VALVE OPERATION . Replace IAC valve as necessary. If IAC valve is okay, check for open or short in IAC valve wiring. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. Repair wiring as necessary. If wiring is okay, replace ECM.