Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Lexus IS 300 and 2002 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: If not using the hand-held tester, start inspection from step 2.

Connect the hand-held tester to the DLC3 and turn the ignition and hand-held tester switch ON. See Figure. Check that the hazard switch can operate in an ACTIVE TEST. If the results are OK, the circuit is OK. Further diagnosis is needed. If the results are not OK, go to the next step.

Check the hazard switch. See CONNECTOR IDENTIFICATION . See INSPECTING HAZARD SWITCH (A/C ECU) CONTINUITY table. If the results are OK, go to the next step. If the results are not OK, replace the hazard switch located on the A/C control with radio receiver assembly. See INSTRUMENT PANEL under REMOVAL & INSTALLATION under INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.

INSPECTING HAZARD SWITCH (A/C ECU) CONTINUITY

Tester Connection	Condition	Specified Condition
A13-1 - Ground	Hazard Switch OFF	No Continuity
A13-2 - Ground	Hazard Switch ON	Continuity

Check the wiring harness and connector between the hazard switch and body ECU. See WIRING DIAGRAMS . If the results are OK, the circuit is OK. Further diagnosis is needed. If the results are not OK, repair or replace the wiring harness or connector.