Inspection Procedure

WARNING: This page is about a different car, the 2003 Lexus GS 430 and 2003 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.

Check voltage between terminals CCS of ECM connector and body ground.
PREPARATION:
1. Remove the ECM with connector still connected.
2. Turn the ignition switch to ON.
CHECK:

Measure voltage between terminals CCS of ECM connector and body ground, when each of the SET/COAST, RESUME/ACCEL and CANCEL is turned ON.

Fig 1: Checking Voltage Between Terminals CCS Of ECM Connector And Body Ground
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Switch Position Table
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Proceed to next circuit inspection shown in problem symptoms table (See PROBLEM SYMPTOMS TABLE ).
2. OK: Go to Next Step
Check control switch continuity.
PREPARATION:
1. Remove the steering wheel pad (See REMOVAL ).
2. Disconnect the control switch connector.
CHECK:

Measure the resistance between terminals 4 and 5 of control switch connector when control switch is operated.

Fig 3: Checking Control Switch Continuity Table
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 4: Switch Continuity Table
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Replace control switch.
2. OK: Go to Next Step
Check main switch continuity.
PREPARATION:
1. Remove the steering wheel pad (See REMOVAL ).
2. Disconnect the control switch connector.
CHECK:

Check the continuity between terminals 4 and 5 of control switch connector when main switch is held ON and OFF.

OK:

Fig 5: Checking Main Switch Continuity
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 6: Main Switch Continuity Table
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Replace control switch.
2. OK: Go to Next Step
Check harness and connector between ECM and cruise control switch, cruise control switch and body ground (Check wire harness, connectors and terminals for damage or looseless, check for Open or Short circuits).
1. NG: Repair or replace harness or connector.
2. OK: Go to Next Step
Check cruise control indicator light (See INSTRUMENT PANEL - TROUBLESHOOTING and COMBINATION METER - COMPONENT INSPECTION ).
1. NG: Replace combination meter.
2. OK: Go to next step.
  Check and replace ECM (Check wire harness, connectors and terminals for damage or looseless, check ECM and body ground, check for Open or Short circuits).