DIAGNOSTIC ITEM 1: Communication With No ECUs Is Possible: Diagnosis

WARNING: This page is about a different car, the 2017 Mitsubishi Mirage. However, it is still accessible from the selected car via links, so may be relevant.

STEP 1. Check the CAN bus lines for short to power supply. Voltage measurement at data link connector.
CAUTION: A digital multimeter should be used. For details refer to SERVICE PRECAUTIONS .

CAUTION: The test wiring harness should be used. For details refer to SERVICE PRECAUTIONS .
1. Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
2. Voltage between data link connector terminal No. 6 (CAN_H) and body ground
  OK: Less than 4.0 V
3. Voltage between data link connector terminal No. 14 (CAN_L) and body ground
  OK: Less than 4.0 V
4. Disconnect the negative battery terminal.
Q: Is the check result normal?
1. YES <Voltage is less than 4.0 V in both CAN_H and CAN_L> : Go to Step 2.
2. NO <Voltage is 4.0 V or more in either CAN_H or CAN_L> : Perform diagnosis item 2 "Diagnose shorts in the power supply to CAN bus line". Refer to Diagnostic Item 2: Diagnose shorts in the power supply to CAN bus line .
STEP 2. Check the CAN bus lines for short to ground. Resistance measurement at data link connector.
CAUTION: A digital multimeter should be used. For details refer to SERVICE PRECAUTIONS .

CAUTION: The test wiring harness should be used. For details refer to SERVICE PRECAUTIONS .
1. Turn the ignition switch to the "LOCK" (OFF) position.
  CAUTION: When measuring the resistance, disconnect the negative battery terminal. For details refer to SERVICE PRECAUTIONS .
2. Ensure that the negative battery terminal is disconnected.
3. Resistance between data link connector terminal No. 6 (CAN_H) and body ground
  OK: 1 kΩ or more
4. Resistance between data link connector terminal No. 14 (CAN_L) and body ground
  OK: 1 kΩ or more
Q: Is the check result normal?
1. YES <Resistance value is 1 kΩ or more in both CAN_H and CAN_L> : Go to Step 3.
2. NO <Resistance value is less than 1 kΩ in either CAN_H or CAN_L> : Perform diagnosis item 3 "Diagnose shorts in the ground to CAN bus line". Refer to Diagnostic Item 3: Diagnose shorts in the ground to CAN bus line .
STEP 3. Check the CAN bus lines for short to each other. Resistance measurement at data link connector.
CAUTION: A digital multimeter should be used. For details refer to SERVICE PRECAUTIONS .

CAUTION: The test wiring harness should be used. For details refer to SERVICE PRECAUTIONS .
1. Turn the ignition switch to the "LOCK" (OFF) position.
  CAUTION: When measuring the resistance, disconnect the negative battery terminal. For details refer to SERVICE PRECAUTIONS .
2. Ensure that the negative battery terminal is disconnected.
3. Resistance between data link connector terminal Nos.6 and 14
  OK: 60 ± 10 Ω
Q: Is the check result normal?
1. YES: The trouble can be an intermittent malfunction (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION .
2. NO <Resistance value is less than 60 ± 10 > : Perform diagnosis Item 4 "Diagnose shorts between CAN_H and L lines". Refer to Diagnostic Item 4: Diagnose shorts between CAN_H and L lines .
3. NO <Resistance value is 1 kΩ or more> : Check the wires between data link connector and joint connector (CAN1) for open circuit, and check the terminal resistors in the engine control module and the ETACS-ECU for open circuit. Then repair or replace if necessary.