No Communication With Engine Control Module/Powertrain Control Module (ECM/PCM)

2001 Mitsubishi Mirage LS, 4D Sedan, StandardSECTION No Communication With Engine Control Module/Powertrain Control Module (ECM/PCM)
  1. Check connectors and wiring between ECM and OBD-II Data Link Connector (OBD-II DLC). If wiring and connectors are okay, 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 MFI relay is okay, go to next step.
  2. Remove MFI relay. Check voltage between ground and MFI relay 4-pin connector terminals No. 3 and 4. If battery voltage exists at each terminal, go to next step. If battery voltage does not exist at each terminal, check connectors and wiring between MFI relay and battery. If problem exists, repair connector or wiring as necessary. If connectors and wiring are okay, check ignition switch.
  3. Reinstall MFI relay. Disconnect ECM harness connector B40. Turn ignition on. Check Red/Yellow wire for voltage between ground and ECM connector B40 terminals No. 12 and 25 (M/T) or B76 terminals No. 41 and 47 (A/T). See Figure . If battery voltage exists at each terminal, go to next step. If battery voltage does not exist at either terminal, repair appropriate wire between MFI relay and ECM.
  4. Turn ignition off. Check Black wire for continuity between ground and ECM connector B40 terminals No. 13 and 26 (M/T) or B76 terminal No. 42 and 48 (A/T). If continuity exists between ground and each terminal, go to next step. If continuity does not exist between ground and each terminal, repair open in appropriate wire between ECM and ground. Ground points are located behind right kick panel and top right side of firewall.
  5. Disconnect ECM 22-pin harness connector B37 (M/T) or B76 (A/T). Turn ignition on. Check Red/Black wire for voltage between ground and ECM connector B37 terminal No. 80 (M/T) or B76 terminal No. 66 (A/T). See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, repair open in wire between battery and ECM.
  6. Check for poor or loose connection at ECM connectors B37 and B40. If problem exists, repair ECM connectors as necessary. If ECM connectors are okay, if problem still exist. Replace ECM.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.