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DTC U0020: CAN-B Bus Off Performance
DTC U0021: CAN-B Bus (HI) Circuit Open
DTC U0022: CAN-B Bus (HI) Shorted to Circuit Ground
DTC U0023: CAN-B Bus (HI) Shorted to Circuit Power Supply
DTC U0024: CAN-B Bus (LO) Circuit Open
DTC U0025: CAN-B Bus (LO) Shorted to Circuit Ground
DTC U0026: CAN-B Bus (LO) Shorted to Circuit Power Supply


caution
  • If the DTC U0020, U0021, U0022, U0023, U0024, U0025, U0026 is set in the occupant classification-ECU, always diagnose the CAN main bus lines.
  • When replacing the ECU, always check that the communication circuit is normal.

DIAGNOSTIC FUNCTION


If the CAN-B circuit malfunction is present, the occupant classification-ECU sets the DTC U0020, U0021, U0022, U0023, U0024, U0025, U0026.

JUDGEMENT CRITERIA


Because of the CAN-B bus circuit malfunction, if occupant classification-ECU becomes unable to perform the normal data transmission, occupant classification-ECU determines that an abnormality is present.

TROUBLESHOOTING HINTS


The CAN bus line 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)Turn the ignition switch to the "ON" position.
(2)Diagnose the CAN bus line.
(3)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the CAN bus line found to be normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).

STEP 2. Recheck for diagnostic trouble code
Check again if the DTC is set to the occupant classification-ECU.

(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 ."
(2)Turn the ignition switch to the "ON" position.
(3)Check if DTC is set.
(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the DTC set?

Replace the front seat cushion frame (RH) (Refer to GROUP 52A, Front Seat Assembly ) <Except RALLIART> or replace the slide adjuster (RH) (Refer to GROUP 52A, Front Seat Assembly ) <RALLIART>.

There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).