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Home >> Mitsubishi >> 2002 >> Montero XLS >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Diagnosis - R4A51, V4A51 & V5A51 >> Diagnostic Tests >> DTC 54 (P1751): A/T Control Relay Circuit Open/Shorted To Ground >> Diagnostic Procedure

Diagnostic Procedure

CAUTION: To prevent damage to scan tool, always turn the ignition off before connecting or disconnecting scan tool.
  1. Using scan tool, monitor A/T control relay output voltage. Battery voltage should exist. Turn ignition off. Is the A/T control relay operating properly? If so, malfunction is intermittent. If not, go to next step.
  2. Check the A/T control relay. See A/T CONTROL RELAY  under COMPONENT TESTS. Is the resistance as specified? If so, go to next step. If not, replace the A/T control relay.
  3. Check A/T control relay 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.
  4. Check the power supply voltage at A/T control relay harness connector. Disconnect the A/T control relay and measure at the harness side. Turn ignition on. Measure the voltage between A/T control relay terminal No. 1 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step  6 . If not, go to next step.
  5. Check power supply circuit harness connectors between A/T control relay and battery for damage. Are the harness connectors in good condition? If so, repair open or short to ground in wire harness between A/T control relay harness connector terminal No. 1 and the battery. If not, repair or replace defective harness connector(s).
  6. Check the continuity at A/T control relay harness connector. Disconnect the A/T control relay and measure at the harness side. Measure the resistance between A/T control relay harness connector terminal No. 2 and ground. Resistance should be less than 2 ohms. Is the resistance as specified? If so, go to step  8 . If not, go to next step.
  7. Check A/T control relay ground circuit harness connectors for damage. Are the harness connectors in good condition? If so, repair open or damage in wire harness between A/T control relay harness connector terminal No. 2 and ground. If not, repair or replace defective harness connector(s).
  8. Check the power supply voltage at A/T control relay harness connector. Disconnect the A/T control relay and measure at the harness connector side. Turn ignition on. Measure the voltage between A/T control relay harness connector terminal No. 4 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step  13 . If not, go to next step.
  9. Check the power supply voltage at PCM harness connector by backprobing. Do not disconnect harness connector. Turn ignition on. Measure the voltage between PCM harness connector terminal No. 50 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to next step. If not, go to step  11 .
  10. Check PCM harness connectors for damage. Are the harness connectors in good condition? If so, repair open in wire harness between A/T control relay harness connector terminal No. 4 and PCM harness connector terminal No. 50. If not, repair or replace defective harness connector(s).
  11. Check wire harness for short to ground between A/T control relay harness connector terminal No. 4 and PCM harness connector terminal No. 50. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  12. Using scan tool, monitor A/T control relay output voltage. Battery voltage should exist. Turn ignition off. Is the A/T control relay 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.
  13. Check the A/T control relay output voltage at PCM harness connector by backprobing between PCM harness connector terminal No. 77 and ground. Battery voltage should exist. Measure the voltage between PCM harness connector terminal No. 89 and ground. Battery voltage should exist. Turn ignition off. Is the voltage as specified? If so, go to step  12 . If not, go to next step.
  14. Check PCM harness connectors for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace defective harness connector(s).
  15. Check wire harness for short to ground, open or damage between A/T control relay harness connector terminal No. 3 and PCM harness connector terminals No. 77 and 89. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  16. Check wire harness for damage between A/T control relay harness connector terminal No. 1 and battery. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  17. Check wire harness for damage between A/T control relay harness connector terminal No. 2 and ground. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  18. Check wire harness for short to ground between A/T control relay harness connector terminal No. 4 and PCM harness connector terminal No. 50. Is the wire harness in good condition? If so, repair short to ground in wire harness between A/T control relay harness connector terminal No. 3 and transmission solenoid valve assembly harness connector terminal No. 9. If not, repair wire harness as necessary.
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