Diagnostic Procedure
WARNING: This page is about a different car, the 2003 Lexus ES 300 and 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
For circuit wiring diagram, see Fig 1.
- Connect the hand-held tester to the DLC3. See Figure. Turn the ignition switch ON and push the hand-held tester main switch ON. Select the item CANCEL SW, SET/COAST SW, RES/ACC MAIN SW, MAIN SW in the DATA LIST and read it's value displayed on the hand-held tester. Read the value of the hand-held tester. See Fig 2. If the results are OK, proceed to the next circuit inspection shown in the problem symptom table. See CRUISE CONTROL PROBLEM SYMPTOMS table. If the results are not good, go to the next step.
- Inspect terminal CCS of the ECM. See Fig 3. If the results are OK, proceed to the next circuit inspection shown in the problem symptom table. See CRUISE CONTROL PROBLEM SYMPTOMS table. If the results are not good, go to the next step.
- Inspect the cruise control main switch assembly. See Fig 4. If the resistance is OK, go to the next step. If the resistance is not good, replace the cruise control main switch assembly. See CRUISE CONTROL MAIN SWITCH ASSEMBLY under REMOVAL & INSTALLATION.
- Check the harness and connector between the battery and the cruise control main switch.
- Check for an open and short circuit in the harness and connector between terminal CCS of the ECM and terminal CCS of the cruise control switch.
- Check for an open and short circuit in the harness and connector between terminal ECC of the cruise control switch and body ground.