Code No. U1102 ASTC-ECU time-out

caution

If diagnosis code U1102 is set in the A/T-ECU <4M4> or engine-A/T-ECU <6G7>, always diagnose the CAN main bus line.
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 <4M4> or engine-A/T-ECU <6G7>, the power supply system to the ASTC-ECU, the ASTC-ECU itself, or the A/T-ECU <4M4> or engine-A/T-ECU <6G7> 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 <4M4> or engine-A/T-ECU <6G7>, 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

. 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 54D - CAN Bus Line Diagnostic Flow

PROBABLE CAUSES

Damaged wiring harness or connector
Malfunction of the ASTC-ECU
Malfunction of the A/T-ECU <4M4>
Malfunction of the engine-A/T-ECU <6G7>

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 54D - Troubleshooting ). and then go to Step 4.

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

Check whether the ASTC system diagnosis codes are set or not.

Q. Is the diagnosis code set?

	YES : Diagnose the ASTC system (Refer to GROUP 35C - Troubleshooting, Inspection Chart For Diagnosis Codes ).

	Go to Step 3.

STEP 3. M.U.T.-III diagnosis code

Reconfirm whether the diagnosis codes are set from A/T-ECU <4M4> or engine-A/T-ECU <6G7>.

(1)Erase the diagnosis code.

(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?

	Go to Step 4.

	Intermittent malfunction in CAN bus line between ASTC-ECU and A/T-ECU <4M4> or engine-A/T-ECU <6G7> (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 A/T diagnosis code output.

Q. Is the diagnosis code set?

	Replace the A/T-ECU <4M4> or engine-A/T-ECU <6G7>.

	The check is end.