Diagnostic Test

TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, record and erase FCM DTC's.
3. Cycle the ignition from on to off 3 times.
4. Turn the ignition on.
5. With the scan tool, read active FCM DTC's.
Q: Does the scan tool display this DTC as active?

Yes :
- Go To 2
No :
- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
CHECK THE (D54) CAN B BUS (-) CIRCUIT FOR A SHORT TO GROUND

Fig 1: Checking CAN B Bus (-) Circuit For Short To Ground
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Turn the ignition off.
2. Disconnect the Front Control Module C1 harness connector.
3. Measure the resistance between ground and the (D54) CAN B Bus (-) circuit.
Q: Is resistance below 1000.0 ohms?

Yes :
- Go To 3
No :
- Go To 4
(D54) CAN B BUS (-) CIRCUIT SHORTED TO GROUND

Fig 2: Checking CAN B Bus (-) Circuit For Short To Ground
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Measure the resistance between ground and the (D54) CAN B Bus (-) circuit.
2. While monitoring the ohmmeter, disconnect each CAN B Bus module one at a time.
NOTE: This is to determine if the short to ground is internal within a module or if the circuit is shorted.

NOTE: Disconnecting an in-line connector can eliminate a module or group of modules from the list of possible causes for this fault. Refer to appropriate SYSTEM WIRING DIAGRAMS article to assist in diagnosis.

Q: Is resistance below 1000.0 ohms with all the CAN B Bus modules disconnected?

Yes :
- Repair the (D54) CAN B Bus (-) circuit for a short to ground.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to ELECTRONIC CONTROL MODULES/MODULE - FRONT CONTROL/DIAGNOSIS AND TESTING).
No :
- Replace the module that when disconnected the short to ground was eliminated, in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to ELECTRONIC CONTROL MODULES/MODULE - FRONT CONTROL/DIAGNOSIS AND TESTING).
CHECK THE (D55) CAN B BUS (+) CIRCUIT FOR A SHORT TO THE (D54) CAN B BUS (-) CIRCUIT

Fig 3: Checking CAN B Bus (+) Circuit For Short To (D54) CAN B Bus (-) Circuit
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Measure the resistance between the (D55) CAN B Bus (+) circuit and (D54) CAN B Bus (-) circuit.
Q: Is resistance below 1000.0 ohms?

Yes :
- Go To 5
No :
- Inspect the wiring and connectors for damage or shorted circuits. If OK, replace the Front Control Module in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to ELECTRONIC CONTROL MODULES/MODULE - FRONT CONTROL/DIAGNOSIS AND TESTING).
(D55) CAN B BUS (+) CIRCUIT SHORTED TO THE (D54) CAN B BUS (-) CIRCUIT

Fig 4: Checking CAN B Bus (+) Circuit For Short To (D54) CAN B Bus (-) Circuit
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
1. Measure the resistance between the (D55) CAN B Bus (+) circuit and (D54) CAN B Bus (-) circuit.
2. While monitoring the ohmmeter, disconnect each CAN B Bus module one at a time.
NOTE: This is to determine if the short together is internal within a module or if the circuits are shorted together.

NOTE: Disconnecting an in-line connector can eliminate a module or group of modules from the list of possible causes for this fault. Refer to appropriate SYSTEM WIRING DIAGRAMS article to assist in diagnosis.

Q: Is resistance below 1000.0 ohms with all the CAN B Bus modules disconnected?

Yes :
- Repair the (D55) CAN B Bus (+) circuit for a short to the (D54) CAN B Bus (-) circuit.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to ELECTRONIC CONTROL MODULES/MODULE - FRONT CONTROL/DIAGNOSIS AND TESTING).
No :
- Replace the module that when disconnected the short to ground was eliminated, in accordance with the service information.
- Perform BODY VERIFICATION TEST - VER 1 . (Refer to ELECTRONIC CONTROL MODULES/MODULE - FRONT CONTROL/DIAGNOSIS AND TESTING).