DTC U0121: ABS/ASC CAN timeout: Diagnosis

WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.

STEP 1. Using scan tool (M.U.T.-III), diagnose the CAN bus line.
CAUTION: To prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
1. Connect scan tool (M.U.T.-III). Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) ."
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?
1. YES: Go to Step 2.
2. NO: Repair the CAN bus line (Refer to DIAGNOSIS ). On completion, go to Step 6.
STEP 2. Using scan tool (M.U.T.-III), read the ASC-ECU diagnostic trouble code.
Check if DTC is stored in the ASC-ECU.

Q: Is the DTC stored?
1. YES: Troubleshoot the ASC-ECU (Refer to DIAGNOSTIC TROUBLE CODE TABLE ). On completion, go to Step 6.
2. NO: Go to Step 3.
STEP 3. Using scan tool (M.U.T.-III), read the ETACS diagnostic trouble code.
Check if DTC U0121 is stored in the ETACS-ECU.

Q: Is the DTC stored?
1. YES: Go to Step 4.
2. NO: Go to Step 5.
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is stored in the SRS-ECU.
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is stored.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC stored?
1. YES: Replace the ASC-ECU. Then, carry out the CAN bus diagnostics. Then go to Step 6.
2. NO: The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the ASC-ECU and the SRS-ECU (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is stored in the SRS-ECU.
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is stored.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC stored?
1. YES: Replace the SRS-ECU. Then, carry out the CAN bus diagnostics. Then go to Step 6.
2. NO: The trouble can be an intermittent malfunction such as a poor connection or open circuit in the CAN bus lines between the ASC-ECU and the SRS-ECU (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
STEP 6. Recheck for diagnostic trouble code.
Check again if the DTC is stored in the SRS-ECU.
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is stored.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC stored?
1. YES: Return to Step 1.
2. NO: The procedure is complete.