Diagnosis & Repair

WARNING: This page is about a different car, the 2003 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.

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 in GENERAL INFORMATION.

For wiring diagram, see Fig 1. For diagnosis and repair see Fig 2-Fig 4 .

Fig 1: Engine Coolant Temperature Circuit Wiring Diagram

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Diagnosis & Repair Of Engine Coolant Temperature Circuit (1 Of 3)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 3: Diagnosis & Repair Of Engine Coolant Temperature Circuit (2 Of 3)

Fig 4: Diagnosis & Repair Of Engine Coolant Temperature Circuit (3 Of 3)