DIAGNOSTIC ITEM 10: Diagnose When The Scan Tool Cannot Receive The Data Sent By ECM: Diagnosis

Required Special Tools:

MB991223: Harness Set
MB992006: Extra Fine Probe
MB992110: Power plant ECU check harness

STEP 1. Check joint connector (CAN3) C-127 <M/T>, joint connector (CAN4) A-14 <TC-SST>, ECM connector B-10 and intermediate connector A-13 <TC-SST> for loose, corroded or damaged terminals, or terminals pushed back in the connector.
CAUTION: The strand end of the twisted wire should be within 10 cm (4 inches) from the connector. For details refer to SERVICE PRECAUTIONS .

Q: Are joint connector (CAN3) C-127 <M/T>, joint connector (CAN4) A-14 <M/T>, ECM connector B-10 and intermediate connector A-13 <TC-SST> in good condition?
1. YES: Go to Step 2.
2. NO: Repair the damaged parts.
STEP 2. Check the wiring harness between joint connector (CAN3) C-127 <M/T> or joint connector (CAN4) A-14 <TC-SST> and ECM connector B-10.
CAUTION: Strictly observe the specified wiring harness repair procedure. For details refer to SERVICE PRECAUTIONS .
1. Disconnect joint connector (CAN3) C-127 and ECM connector B-10, and check the wiring harness.
2. Check the wiring harness between joint connector (CAN3) C-127 (terminal 10) and ECM connector B-10 (terminal 90) <M/T>
  OK: Continuity exists (2 Ω or less)
  
  Fig 1: Measuring Resistance Between Joint Connector C-127 Terminal 10 & ECM Connector B-10 Terminal 90
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Check the wiring harness between joint connector (CAN3) C-127 (terminal 21) and ECM connector B-10 (terminal 91) <M/T>
  OK: Continuity exists (2 Ω or less)
  
  Fig 2: Measuring Resistance Between Joint Connector C-127 Terminal 21 & ECM Connector B-10 Terminal 91
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
4. Check the wiring harness between joint connector (CAN4) A-14 (terminal 6) and ECM connector B-10 (terminal 90) <TC-SST>
  OK: Continuity exists (2 Ω or less)
  
  Fig 3: Measuring Resistance Between Joint Connector A-14 Terminal 6 & ECM Connector B-10 Terminal 90
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
5. Check the wiring harness between joint connector (CAN4) A-14 (terminal 19) and ECM connector B-10 (terminal 91) <TC-SST>
  OK: Continuity exists (2 Ω or less)
  
  Q: Is the wiring harness between joint connector (CAN3) C-127 <M/T> or joint connector (CAN4) A-14 <TC-SST> and ECM connector B-10 in good condition?
  1. YES: Check the power supply circuit of the ECM. Refer to MULTIPORT FUEL INJECTION (MFI) -- LANCER EVOLUTION .
  2. NO: Repair the wiring harness between joint connector (CAN3) C-127 <M/T> or joint connector (CAN4) A-14 <TC-SST> and ECM connector B-10.
    
    Fig 4: Measuring Resistance Between Joint Connector A-14 Terminal 19 & ECM Connector B-10 Terminal 91
    Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.