Code No.U1122 ABS-ECU or TCL/ASC-ECU failure information


caution
  • If the electric power steering-ECU sets diagnosis code No.U1122, diagnose the CAN bus lines. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.


TROUBLE JUDGMENT
The electric power steering-ECU receives vehicle speed data (wheel speed sensor data) from the ABS-ECU or the TCL/ASC-ECU through the CAN bus lines. If the ECU receives vehicle speed data (wheel speed sensor data) containing failure information twice, diagnosis code U1122 will be set.

COMMENTS ON TROUBLE SYMPTOM
The M.U.T.-III shows a diagnosis code status as active
  • The wheel speed sensor system (of the ABS-ECU or TCL/ASC-ECU), the ABS-ECU, the TCL/ASC-ECU or the electric power steering-ECU may be defective.
The M.U.T.-III shows a diagnosis code status as stored
  • Carry out diagnosis by referring to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to treat past trouble ). Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the CAN bus lines between the engine-ECU <M/T> or engine-A-M/T-ECU <Automated manual transmission> and the electric power steering-ECU.
    note For a The M.U.T.-III shows a diagnosis code status as stored, you can not find it by the M.U.T.-III CAN bus diagnostics even if there is any failure in CAN bus lines. In this case, refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points-How to Cope with Intermittent Malfunction and check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).

PROBABLE CAUSES

  • Defective harness wire(s) or connector(s)
  • Malfunction of the ABS-ECU or TCL/ASC-ECU
  • Malfunction of the electric power steering-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
(1)Connect M.U.T.-III to the 16-pin diagnosis connector.
(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 check result normal?

Go to Step 2.

Repair the CAN bus line (Refer to GROUP 54C - CAN bus line Diagnostic flow ).

STEP 2. M.U.T.-III other system diagnosis code

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Check that an ABS system or TCL/ASC diagnosis code is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the diagnosis code set?

Diagnose the ABS system or the TCL/ASC (Refer to GROUP 35B - Troubleshooting - Check chart for diagnosis code or GROUP 35C - Troubleshooting - Check chart for diagnosis code ).

Go to Step 3.

STEP 3. Check whether the diagnosis code is reset

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Recheck whether diagnosis code C1122 is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the diagnosis code set?

Replace the electric power steering-ECU (Refer to ). Then go to Step 4.

A poor connection, open circuit or other intermittent malfunction is present in the CAN bus lines between the ABS-ECU or TCL/ASC-ECU and the wheel speed sensors. Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

STEP 4. Check whether the diagnosis code is reset

caution Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.
Check again if the diagnosis code is set.
(1)Turn the ignition switch to the "ON" position.
(2)Erase the diagnosis code.
(3)Turn the ignition switch to the "LOCK" (OFF) position.
(4)Turn the ignition switch to the "ON" position.
(5)Recheck whether diagnosis code C1522 is set.
(6)Turn the ignition switch to the "LOCK" (OFF) position.
(7)Disconnect M.U.T.-III.

Q. Is the diagnosis code set?

Replace the hydraulic unit (Refer to GROUP 35B - ABS - Hydraulic Unit or GROUP 35C - TCL/ASC - Hydraulic Unit ).

This diagnosis is complete.