Code No.U1102 CAN communication time-out with ABS-ECU or TCL/ASC-ECU


caution
  • If more than three minutes elapse after the ignition switch is turned ON without starting engine, the electric power steering-ECU may set diagnosis codes U1100 and U1102 as the M.U.T.-III shows a diagnosis code status as stored.
  • If the electric power steering-ECU sets diagnosis code No.U1102, 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 through the CAN bus lines. If the electric power steering-ECU cannot receive the vehicle speed data (wheel speed sensor data) from the ABS-ECU or the TCL/ASC for 60 seconds, diagnosis code U1102 will be set.

COMMENTS ON TROUBLE SYMPTOM
The M.U.T.-III shows a diagnosis code status as active
  • Defective harness wire(s) or connector(s) in the CAN bus lines between the ABS-ECU or TCL/ASC-ECU and the electric power steering-ECU, or the power supply to these ECUs, or the ECUs themselves are 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 ABS-ECU or TCL/ASC-ECU and the electric power steering-ECU, and the power supply to the ABS-ECU or TCL/ASC-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 ). Then go to Step 2.

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 system 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 system (Refer to GROUP 35B - Troubleshooting - Check chart for daiagnosis code or GROUP 35C - Troubleshooting - Check chart for daiagnosis 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)Start the engine and wait for at least 60 seconds.
(6)Recheck whether diagnosis code U1102 is set.
(7)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is diagnosis code U1102 set?

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

Go to Step 4.

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)Check if the diagnosis code 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.