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Home >> Mitsubishi >> 2001 >> Montero XLS >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Diagnosis - R4A51, V4A51 & V5A51 >> Symptom Tests >> Test O: Vehicle Shifts Differently With A/C Engaged >> Diagnostic Procedure (Montero)

Diagnostic Procedure (Montero)

NOTE: For circuit identification see Fig 1 .
  1. Using scan tool, monitor dual pressure switch. When the A/C is in operation, the scan tool display should indicate ON. When the A/C is not in operation, the scan tool display should indicate OFF. Is the dual pressure switch operating properly? If so, malfunction is intermittent. If not, go to next step.
  2. Check dual pressure switch harness connector for damage. Is the harness connector in good condition? If so, go to next step. If not, repair or replace defective harness connector.
  3. Check the power supply voltage at dual pressure switch harness connector. Disconnect the dual pressure switch harness connector and measure at the harness side. Start the engine and run at idle. Measure the voltage between dual pressure switch harness connector terminal No. 2 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step  9 . If not, go to next step.
  4. Check the power supply voltage at A/C-ECU harness connector D-23 and automatic compressor controller harness connector D-119 by backprobing. Do not disconnect harness connectors. Start the engine and run at idle. Operate the air conditioning. Measure the voltage between A/C-ECU harness connector D-23 terminal No. 5 and ground, then measure the voltage between automatic compressor controller harness connector D-119 terminal No. 4 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step  8 . If not, go to next step.
  5. Check A/C-ECU harness connector D-23, automatic compressor controller harness connector D-119 and intermediate harness connector D-28 for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace defective harness connector(s).
  6. Check wire harness for short to ground between dual pressure switch harness connector terminal No. 2 and A/C- ECU harness connector D-23 terminal No. 5, and automatic compressor controller harness connector D-119 terminal No. 4. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  7. Using scan tool, monitor dual pressure switch. When the A/C is in operation, the scan tool display should indicate ON. When the A/C is not in operation, the scan tool display should indicate OFF. Turn ignition off. Is the dual pressure switch operating properly? If so, malfunction is intermittent. If not, check the air conditioning system. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
  8. Check A/C-ECU harness connector D-23, automatic compressor controller harness connector D-119 and intermediate harness connector D-28 for damage. Are the harness connectors in good condition? If so, repair open in wire harness between A/C-ECU harness connector D-23 terminal No. 5, automatic compressor controller harness connector D-119 terminal No. 4 and dual pressure switch harness connector terminal No. 2. If not, repair or replace the defective harness connector(s).
  9. Check the dual pressure switch output voltage at PCM harness connector by backprobing. Do not disconnect harness connector. Start the engine and run at idle. Operate the air conditioning. Measure the voltage between PCM harness connector terminal No. 83 and ground. When the air conditioning is in operation, battery voltage should exist. When the air conditioning is not in operation, the voltage should be 0.5 volt or less. Turn ignition off. Is the voltage as specified? If so, go to step  14 . If not, go to next step.
  10. Check PCM harness connectors and intermediate harness connector A-03 for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace the defective harness connector(s).
  11. Check wire harness for short to ground or open between dual pressure switch connector terminal No. 1 and PCM harness connector terminal No. 83. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  12. Check the dual pressure switch. See DUAL PRESSURE SWITCH  under COMPONENT TESTS. Is the dual pressure switch operating properly? If so, go to next step. If not, replace the dual pressure switch. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
  13. Using scan tool, monitor dual pressure switch. When the A/C is in operation, the scan tool display should indicate ON. When the A/C is not in operation, the scan tool display should indicate OFF. Is the dual pressure switch operating properly? If so, malfunction is intermittent. If not, possible faulty PCM exists. Replace the PCM if necessary. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION.
  14. Check PCM harness connectors for damage. Are the harness connectors in good condition? If so, go to step  13 . If not, repair or replace defective harness connector(s).
Fig 1: Identifying Dual Pressure Switch System Circuit (Montero)
G00148958Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
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