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Home >> Mitsubishi >> 1997 >> Galant LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> Scan Tool Will Not Communicate >> No Communication With PCM

No Communication With PCM

  1. Check connectors and wiring harness between PCM and DLC and between PCM and power supply. If wiring and connectors are okay, check MFI relay. See RELAYS in SYSTEM/COMPONENT TESTS article. If MFI relay is okay, go to next step.
  2. Remove MFI relay. Check voltage between ground and MFI relay connector terminal No. 3. If battery voltage exists, go to next step. If battery voltage does not exist, check wiring harness between MFI relay and battery.
  3. Turn ignition on. Check voltage between ground and MFI relay connector terminal No. 4. If battery voltage exists, go to next step. If battery voltage does not exist, check connectors and wiring harness between ignition switch and MFI relay. If connectors and wiring are okay, check ignition switch.
  4. Disconnect PCM connector. Turn ignition on. Check voltage between ground and PCM connector terminal No. 82. If battery voltage exists, go to next step. If battery voltage does not exist, check junction connector between MFI relay connector and PCM and wiring harness between ignition switch connector and PCM. If wiring and connectors are okay, check ignition switch.
  5. Check voltage between ground and terminal No. 38. If battery voltage exists, go to next step. If battery voltahge does not exist, check connectors and wiring harness between MFI relay and PCM.
  6. Turn ignition on. Check voltage between ground and PCM connector terminals No. 12 and 25. If battery voltage exists, go to next step. If battery voltage does not exist, check connectors and wiring harness between MFI relay and PCM.
  7. Check continuity between ground and PCM connector terminals No. 13 and 26. If continuity exists, go to next step. If continuity does not exist, check wiring harness between ground and PCM.
  8. Check voltage between ground and PCM connector terminal No. 60. If battery voltage exists, check PCM connector. If PCM connector is okay, replace PCM. If battery voltage does not exist, check wiring harness between PCM and battery.
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