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Home >> Mitsubishi >> 2003 >> Montero XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Testing Procedure >> Scan Tool Will Not Communicate >> No Communication With Powertrain Control Module (PCM)
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No Communication With Powertrain Control Module (PCM)

  1. Turn ignition off. Check PCM connector D-134 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. If problem does not exist, go to next step.
  2. Check for open or short to ground in wire between OBD-II DLC terminal No. 7 (Red/White wire) and PCM connector D-134 terminal No. 74 (Green/Orange wire). If problem exists, repair Red/White wire or Green/Orange wire. If problem does not exist, go to next step.
  3. Remove MFI relay. Check MFI relay connector for loose, damaged, or corroded terminals. If problem exists, repair or replace connector. If problem does not exist, go to next step.
  4. Check MFI relay. See FUEL PUMP RELAY & MFI RELAY under RELAYS under MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING article. If problem exists, replace MFI relay. If problem does not exist, install MFI relay and go to next step.
  5. Measure voltage between ground and MFI relay connector terminals No. 2 and 3. If battery voltage exists at both terminals, go to next step. If battery voltage does not exist at either or both terminals, repair White/Black wire between MFI relay connector and fusible link No. 5 (20-amp) located in engine compartment relay box.
  6. Disconnect PCM connector D-133. Check PCM connector D-133 for loose, damaged, or corroded terminals. If problem exists, repair or replace connector as necessary. If problem does not exist, go to next step.
  7. Turn ignition on. Measure voltage between ground and PCM connector D-133 terminal No. 50 (Blue/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, check Blue/Black wire between ignition switch and PCM. If problem exists, repair Blue/Black between ignition switch and PCM. If problem does not exist, check ignition switch. Repair as necessary.
  8. Turn ignition off. Disconnect PCM 27-pin connector D-133. Measure voltage between ground and PCM connector D-133 terminal No. 58 (White/Black wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair an open circuit between fusible link (5) and PCM connector D-133 (terminal No. 58), located in engine compartment relay box.
  9. Check for continuity between ground and PCM connector D-133 terminals No. 33 (Black wire) and No. 42 (Black wire). If continuity exists at each terminal, go to next step. If continuity does not exist at either terminal, repair appropriate Black wire between ground and PCM.
  10. Measure voltage between ground and PCM connector D-133 terminal No. 57 (White/Blue wire). If battery voltage exists, go to next step. If battery voltage does not exist, repair White/Blue wire between PCM and MFI relay.
  11. Connect jumper wire between ground and PCM connector D-133 terminal No. 57 (White/Blue wire). MFI relay should audibly click. Measure voltage between ground and PCM connector D-133 terminals No. 34 (Red wire) and No. 43 (Red wire). If battery voltage exists at each terminal, replace PCM. If battery voltage does not exist at either terminal, repair appropriate Red wire between MFI relay and PCM.
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