Diagnostic Procedure (Montero)
NOTE:
For circuit identification see Fig 1
.
- Using scan tool, monitor overdrive off signal (auto-cruise ECM signal). Start the engine and test drive the vehicle. Operate the auto-cruise. When driving vehicle on level road, the scan tool display should indicate OFF. When driving vehicle on uphill road, the scan tool display should indicate ON. Turn ignition off. Is the sensor operating properly? If so, malfunction may be intermittent. If not, go to next step.
- Check the auto-cruise system. See appropriate CRUISE CONTROL SYSTEMS article in ACCESSORIES & EQUIPMENT. Is the auto-cruise system operating properly? If so, go to next step. If not, repair as necessary. Check the symptom.
- Check the signal voltage at PCM harness connector by backprobing. Do not disconnect harness connector. Turn ignition on. Measure the voltage between PCM harness connector terminal No. 75 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step 5 . If not, go to next step.
- Check PCM harness connectors for damage. Are the harness connectors in good condition? If so, possible faulty PCM exists. Replace the PCM if necessary. See POWERTRAIN CONTROL MODULE under REMOVAL & INSTALLATION. If not, repair or replace defective harness connector(s).
- Check the signal voltage at auto-cruise control-ECU harness connector D-12 by backprobing. Do not disconnect. Turn ignition on. Measure the voltage between auto-cruise control-ECU harness connector D-12 terminal No. 3 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step 7 . If not, go to next step.
- Check wire harness for short to ground, open or damage between PCM harness connector terminal No. 75 and auto-cruise control-ECU harness connector D-12 terminal No. 3. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
- Check auto-cruise control-ECU harness connector D-12 for damage. Is the harness connector in good condition? If so, replace the auto-cruise control-ECU. If not, repair or replace defective harness connector.