Code No. U1102 ASTC-ECU time-out


caution
  • If diagnosis code U1102 is stored in the A/T-ECU, always diagnose the CAN main bus line. If there is any fault in the CAN bus lines, an incorrect diagnosis code may be stored.
  • Whenever the ECU is replaced, ensure that the communication circuit is normal.

DIAGNOSIS CODE SET CONDITIONS


Current trouble
  • Connector(s) or wiring harness in the CAN bus lines between the ASTC-ECU and the A/T-ECU, the power supply system to the ASTC-ECU, the ASTC-ECU itself, or the A/T-ECU may be defective.
Past trouble
  • Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the CAN bus lines between the ASTC-ECU and the A/T-ECU, and the power supply system to the ASTC-ECU. For diagnosis procedures, refer to "How to cope with past trouble" (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points ).
    note For a past trouble, you may 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 Malfunctions ). and check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the diagnosis code, which is stored regarding the CAN communication-linked ECUs (Refer to GROUP 54C, Explanation about the M.U.T.-III CAN Bus Diagnostics ).

PROBABLE CAUSES



  • Damaged wiring harness or connector
  • Malfunction of the ASTC-ECU
  • Malfunction of the A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics
Using M.U.T.-III, perform CAN bus line diagnosis.

Q. Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis - Can Bus Diagnostic Chart ), and then go to Step 4.

STEP 2. M.U.T.-III other system diagnosis codes
Check whether the ASTC system diagnosis codes are stored or not.

Q. Is the diagnosis code stored?
YES : Diagnose the ASTC system (Refer to GROUP 35C, Troubleshooting ).
Go to Step 3.

STEP 3. M.U.T.-III diagnosis code
Reconfirm whether the diagnosis codes are stored in the A/T-ECU.
(1)Erase the diagnosis code.
(2)Turn the ignition switch to ON position.
(3)Check if the diagnosis code is stored.

Q. Is the diagnosis code stored?
Go to Step 4.
Intermittent malfunction in CAN bus line between ASTC-ECU and A/T-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

STEP 4. Replace the ASTC-ECU
After replacing the ASTC-ECU, re-check the stored A/T diagnosis code.

Q. Is the diagnosis code stored?
Replace the A/T-ECU.
The check is end.