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Home >> Mitsubishi >> 2003 >> Diamante LS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Self-Diagnostic System >> Scan Tool Will Not Communicate >> No Communication With PCM

No Communication With PCM

  1. Check PCM 28-pin connector B-110, OBD-II Data Link Connector (OBD-II DLC) and in-line connector B-41 (20-pin), located behind center of dash for broken, bent, pushed out or corroded terminals. See Figure and Figure . Repair as necessary. If connectors are okay, ensure original problem is no longer present. If original problem is still present, check wiring harness between PCM and OBD-II DLC. Repair as necessary. If wiring is okay, go to next step.
  2. Remove MFI relay. See Figure. Check for continuity between MFI relay terminals No. 2 and No. 4. See Figure. Continuity should exist. Check for continuity between MFI relay terminals No. 1 and No. 3. Continuity should not exist. If continuity is as specified, go to next step. If continuity is not as specified, replace MFI relay.
  3. Connect battery voltage to MFI relay terminal No. 4 and battery ground to terminal No. 2. Check for continuity between MFI relay terminals No. 1 and No. 3. Continuity should exist. If continuity is not as specified, replace MFI relay. If continuity is as specified, go to next step.
  4. Measure voltage between ground and MFI relay harness connector terminal No. 3 (White/Black wire). If battery voltage is present, go to next step. If battery voltage is not present, check wiring harness between MFI relay and battery. Repair as necessary.
  5. Measure voltage between ground and MFI relay harness connector terminal No. 4 (White/Black wire). If battery voltage is present, go to next step. If battery voltage is not present, check wiring harness between MFI relay and battery. Repair as necessary.
  6. Install MFI relay. Disconnect PCM 35-pin connector B-108 and PCM 26-pin connector B-109. Turn ignition on. Measure voltage between ground and PCM 35-pin harness connector B-108 terminal No. 21 (White/Red wire). See Figure and Figure . If battery voltage is present, go to next step. If battery voltage is not present, check MFI relay connector, junction block connector B-77 and in-line connector B-43 (6-pin), located behind center of dash, for broken, bent, pushed out or corroded terminals. See Figure. Repair as necessary. If connectors are okay, ensure original problem is no longer present. If original problem is still present, check wiring harness between ignition switch and PCM.
  7. Measure voltage between ground and PCM 26-pin harness connector B-109 terminal No. 49 (Black/White wire). See Figure. If battery voltage is present, go to next step. If battery voltage is not present, repair wiring harness between MFI relay and PCM.
  8. Energize MFI relay by connecting jumper wire between ground and PCM 26-pin harness connector B-109 terminal No. 49 (Black/White wire). Measure voltage between ground and PCM harness connector terminal No. 41 (Red wire). If battery voltage is present, go to next step. If battery voltage is not present, repair wire harness between MFI relay and PCM.
  9. Turn ignition off. Disconnect jumper wire. Check continuity between ground and PCM 26-pin harness connector B-109 terminals No. 42 (Black wire) and No. 48 (Black wire). If continuity exists at each terminal, go to next step. If continuity does not exist at each terminal, repair wire harness between ground and PCM.
  10. Measure voltage between ground and PCM 26-pin harness connector B-109 terminal No. 66 (White/Black wire). If battery voltage is present, check PCM 35-pin connector B-108 and PCM 26-pin connector B-109 for broken, bent, pushed out or corroded terminals. Repair as necessary. If connectors are okay, ensure original problem is no longer present. If original problem is still present, replace PCM. If battery voltage is not present, go to next step.
  11. Check junction block connectors B-78 and B-84, and in-line connector B-41 (20-pin), located behind center of dash, for broken, bent, pushed out or corroded terminals. See Figure and Figure . Junction block is located at left side of dash panel below steering wheel. Repair as necessary. If connectors are okay, ensure original problem is no longer present. If original problem is still present, check wiring harness between PCM and battery. Repair as necessary.
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