Inspection Procedure 12: Check the CAN box unit power supply circuit.: Diagnosis

Required Special Tools:

MB991223: Harness Set
MB992006: Extra Fine Probe

STEP 1. Check CAN box unit connectors C-13 for loose, corroded or damaged terminals, or terminals pushed back in the connector.
Q: Is CAN box unit connectors C-13 in good condition?

YES: Go to Step 2.

NO: Repair or replace the damaged component(s). Refer to HARNESS CONNECTOR INSPECTION .
STEP 2. Check the ground circuit to the CAN box unit. Measure the resistance at CAN box unit connectors C-13.
1. Disconnect CAN box unit connector C-13 and measure the resistance available at the wiring harness side of the connector.
2. Measure the resistance value between CAN box unit connector C-13 terminal 1 and ground.
  - The resistance should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?

YES: Go to Step 4.

NO: Go to Step 3.

Fig 1: Measuring Resistance Value Between CAN Box Unit Connector C-13 Terminal 1 And Ground
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 3. Check the wiring harness between CAN box unit connector C-13 (terminal 1) and the ground.
- Check the ground wires for open circuit.
Q: Is the wiring harness between CAN box unit connector C-13 (terminal 1) and the ground in good condition?

YES: No action is necessary and testing is complete.

NO: The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary.
STEP 4. Check the battery power supply circuit to the CAN box unit. Measure the voltage at CAN box unit connectors C-13.
1. Disconnect CAN box unit connectors C-13 measure the voltage available at the wiring harness side of the connector.
2. Measure the voltage between CAN box unit connector C-13 terminal 2 and ground.
  - The voltage should measure approximately 12 volts (battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery positive voltage)?

YES: Go to Step 6.

NO: Go to Step 5.

Fig 2: Measuring Voltage Between CAN Box Unit Connector C-13 Terminal 2 And Ground
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
STEP 5. Check the wiring harness between CAN box unit connector C-13 (terminal 2) and fusible link (36).
- Check the power supply line for open circuit and short circuit.
  NOTE: Also check intermediate connector C-17 and ETACS-ECU connectors C-307 and C-317 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-17 or ETACS-ECU connector C-307 or C-317 is damaged, repair or replace the connector as described in HARNESS CONNECTOR INSPECTION .
Q: Is the wiring harness between CAN box unit connector C-13 (terminal 2) and fusible link (36) in good condition?

YES: No action is necessary and testing is complete.

NO: The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. The system should communicate with the CAN box unit normally.
STEP 6. Check the wiring harness between CAN box unit connector C-13 (terminal 10) and fusible link (37).
- Check the power supply line for open circuit and short circuit.
  NOTE: Also check intermediate connector C-17 and ETACS-ECU connectors C-309 and C-315 for loose, corroded, or damaged terminals, or terminals pushed back in the connector. If intermediate connector C-17 or ETACS-ECU connectors C-309 or C-315 is damaged, repair or replace the connector as described in HARNESS CONNECTOR INSPECTION .
Q: Is the wiring harness between CAN box unit connector C-13 (terminal 10) and fusible link (37) in good condition?

YES: No action is necessary and testing is complete.

NO: The wiring harness may be damaged or the connector(s) may have loose, corroded or damaged terminals, or terminals pushed back in the connector. Repair the wiring harness as necessary. The system should communicate with the CAN box unit normally.