Mitsubishi Multi Communication System (MMCS)
DTC U0154: OCM (occupant classification-ECU) CAN time-out
CAUTION:
If DTC U0154 is set, be sure to diagnose the CAN bus line.
CAUTION:
When replacing the CAN box unit, always check that the communication circuit is normal. (Check that the voltage is 10 V or more.)
DIAGNOSTIC FUNCTION
When the signals from occupant classification-ECU cannot be received, the CAN box unit sets DTC U0154.
JUDGMENT CRITERIA
With the ignition switch in the ON position, system voltage between 10 - 16 volts (data from ETACS-ECU), power supply fuse(IOD fuse) is OK, or odometer value is 80.5 km (50 miles) or more, and the communications with occupant classification-ECU cannot be established for 2,500 ms or more, the CAN box unit determines that a problem has occurred.
TROUBLESHOOTING HINTS
- The CAN bus line may be defective.
- The CAN box unit may be defective.
- The occupant classification-ECU may be defective.
DIAGNOSIS
Required Special Tools:
- MB991958 Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicles Communication Interface (V.C.I.)
- MB991827 M.U.T.-III USB Cable
- MB991910 M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
(1)
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.
Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III) Scan Tool Testing and Procedures."
(2)Turn the ignition switch to the "ON" position.
(3)Diagnose the CAN bus line.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the CAN bus line found to be normal?
YES Go to Step 2.
NO Repair the CAN bus line CAN Bus Diagnostics Chart).
STEP 2. Using scan tool MB991958, read the occupant classification-ECU diagnostic trouble code.
Check if DTC is set to the occupant classification-ECU.
Q. Is the DTC set?
YES Troubleshoot the SRS Occupant Classification).
NO Go to Step 3.
STEP 3. Using scan tool MB991958, read the combination meter diagnostic trouble code.
Check if the DTC U0154 is set to the combination meter.
Q. Is the DTC set?
YES Go to Step 4.
NO Go to Step 5.
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set to the CAN box unit.
(1)Erase the DTC.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)Check if DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the DTC set?
YES Replace the occupant classification-ECU.
NO The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the occupant classification-ECU and the CAN box unit How to Cope With Intermittent Malfunctions).
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set to the CAN box unit.
(1)Erase the DTC.
(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(3)Check if DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q. Is the DTC set?
YES Replace the CAN box unit.
NO The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the occupant classification-ECU and the CAN box unit How to Cope With Intermittent Malfunctions).