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DTC U0121 ABS/ASC CAN timeout
 
 
caution
  • If DTC U0121 is set in the BSW-ECU (slave), always diagnose the CAN bus line.
  • Before replacing the ECU, ensure that the power supply circuit, the ground circuit and the communication circuit are normal.
 
 
OPERATION
The BSW-ECU (slave) communicates with the ASC-ECU via the gateway-ECU and the BSW-ECU (master) over CAN bus lines.
 
 
CHECK CONDITION
Ignition switch is in the ON position.
 
 
DIAGNOSTIC FUNCTION AND JUDGMENT CRITERIA
If the BSW-ECU (slave) cannot receive any signal from the ASC-ECU for at least 2.5 seconds, the ECU sets DTC U0121.
 
 
TROUBLESHOOTING HINTS
  • Power supply to the ASC-ECU fails
  • The ASC-ECU may be defective
  • Power supply to the gateway-ECU fails
  • The gateway-ECU may be defective
  • The BSW-ECU (master/slave) may be defective
  • The CAN bus may be defective
  • The local CAN bus may be defective
 
 
DIAGNOSIS
STEP 1. Check whether the BSW-ECU sets a DTC.
Check whether DTC No. C2332 and/or U0121 are set in the BSW-ECU (master).
cautionTo 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).
Connect scan tool (M.U.T.-III). Refer to "How to connect the Scan Tool (M.U.T.-III) ."
Is the DTC set?
(Only No. C2332 is set or both codes are set) : Follow diagnostic trouble code procedure No. C2332 for the BSW-ECU (master) (Refer to ).
(Only No. U0121 is set) : Follow diagnostic trouble code procedure No. U0121 for the BSW-ECU (master) (Refer to ).
Go to Step 2.
 
STEP 2. Check whether the DTC is set again.
Check again if the DTC is set in the BSW-ECU (slave).
(1) Erase the DTC.
(2) Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.
(3) Check if the DTC is set.
Is the DTC set?
Replace the BSW-ECU (slave).
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).