DIAGNOSTIC ITEM 1: Diagnose when the scan tool cannot receive the data sent by ETACS-ECU: Diagnosis

Required Special Tools:

MB991223: Harness Set
MB992006: Extra Fine Probe
MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)
- MB991827: M.U.T.-III USB Cable
- MB991910: M.U.T.-III Main Harness A

STEP 1. Check data link connector C-34 and ETACS-ECU connector C-301 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 data link connector C-34 and ETACS-ECU connector C-301 in good condition?
1. YES: Go to Step 2.
2. NO: Repair the damaged parts.
STEP 2. Check the wiring harness between data link connector C-34 and ETACS-ECU connector C-301 for open circuit.
CAUTION: Strictly observe the specified wiring harness repair procedure. For details refer to SERVICE PRECAUTIONS .
1. Disconnect the scan tool and ETACS-ECU connector C-301, and check the wiring harness.
2. Check the wiring harness between data link connector C-34 (terminal 6) and ETACS-ECU connector C-301 (terminal 5) < CAN_H >
  OK: Continuity exists (2 Ω or less)
  
  Fig 1: Checking Wiring Harness Between Data Link Connector C-34 (Terminal 6) And ETACS-ECU Connector C-301 (Terminal 5)
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Check the wiring harness between data link connector C-34 (terminal 14) and ETACS-ECU connector C-301 (terminal 4) < CAN_L >
  OK: Continuity exists (2 Ω or less)
Q: Is the wiring harness between data link connector C-34 and ETACS-ECU connector C-301 in good condition?
1. YES: Go to Step 3.
2. NO: Repair the wiring harness between data link connector C-34 and ETACS-ECU connector C-301.
  
  Fig 2: Checking Wiring Harness Between Data Link Connector C-34 (Terminal 14) And ETACS-ECU Connector C-301 (Terminal 4)
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 3. Check the wiring harness between data link connector C-34 and ETACS-ECU connector C-301 for a short to ground. Measure the resistance at data link connector C-34.
CAUTION: Disconnect the negative battery terminal. For details refer to SERVICE PRECAUTIONS .

CAUTION: A digital multimeter should be used. For details refer to TEST EQUIPMENT .

CAUTION: The test wiring harness should be used. For details refer to SERVICE PRECAUTIONS .
1. Disconnect the scan tool and ETACS-ECU connector C-301, and measure the resistance at the wiring harness side of data link connector C-34.
2. Measure the resistance between data link connector terminal 6 and body ground. < CAN_H >
  OK: 1 kΩ or more
  
  Fig 3: Measuring Resistance Between Data Link Connector Terminal 6 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Measure the resistance between data link connector terminal 14 and body ground. < CAN_L >
  OK: 1 kΩ or more
Q: Do all the resistances measure 1 kΩ or more?
1. YES: Go to Step 4.
2. NO: Repair the wiring harness between data link connector C-34 and ETACS-ECU connector C-301.
  
  Fig 4: Measuring Resistance Between Data Link Connector Terminal 14 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 4. Check the wiring harness between data link connector C-34 and ETACS-ECU connector C-301 for a short to the power supply. Measure the voltage at data link connector C-34.
1. Disconnect the scan tool and ETACS-ECU connector C-301, and measure the resistance at the wiring harness side of data link connector C-34.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between data link connector terminal 6 and body ground. < CAN_H >
  OK: 1 V or less
  
  Fig 5: Measuring Voltage Between Data Link Connector Terminal 6 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
4. Measure the voltage between data link connector terminal 14 and body ground. < CAN_L >
  OK: 1 V or less
Q: Do all the voltage measure 5 v or less?
1. YES: Go to Step 5.
2. NO: Repair the wiring harness between data link connector C-34 and ETACS-ECU connector C-301.
  
  Fig 6: Measuring Voltage Between Data Link Connector Terminal 14 And Body Ground
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 5. Check the wiring harness between data link connector C-34 and ETACS-ECU connector C-301 for line-to-line short. Measure the resistance at data link connector C-34.
1. Disconnect the scan tool and ETACS-ECU connector C-301, and measure the resistance at the wiring harness side of data link connector C-34.
2. Measure the resistance between data link connector terminal 6 and 14.
  OK: No continuity
Q: Is the check result normal?
1. YES: Go to Step 6.
2. NO: Repair the wiring harness between data link connector C-34 and ETACS-ECU connector C-301.
  
  Fig 7: Measuring Resistance Between Data Link Connector Terminal 6 And 14
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 6. Using scan tool MB991958, diagnose the CAN bus line.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
  
  Fig 8: Connecting Special Tool MB991910 To Data Link Connector
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
3. Diagnose CAN bus lines, and check if the scan tool screen is as shown in the illustration.
Q: Does the scan tool screen correspond to the illustration?
1. YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
2. NO: Replace the ETACS-ECU.
  
  Fig 9: CAN Bus Lines Communication Diagram
  Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.