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 2.
STEP 2. Using scan tool (M.U.T.-III), read the ASC diagnostic trouble code
Check if DTC is stored in the ASC-ECU.

Q: Is the DTC stored?
1. YES: Diagnose the ASC. Refer to DIAGNOSTIC TROUBLE CODE CHART .
2. NO: Go to Step 3
STEP 3. Using scan tool (M.U.T.-III), read the ETACS diagnostic trouble code.
Check if the DTC No. U0121 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 LDW-ECU.
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is stored.
Q: Is the DTC stored?
1. YES: Replace the ASC-ECU.
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 LDW-ECU (HOW TO COPE WITH INTERMITTENT MALFUNCTION ).
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is stored in the LDW-ECU.
1. Erase the DTC.
2. Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
3. Check if DTC is stored.
Q: Is the DTC stored?
1. YES: Replace the LDW-ECU.
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 LDW-ECU (HOW TO COPE WITH INTERMITTENT MALFUNCTION ).