Code No. U1102 ASTC-ECU Time-out <Vehicles with ASTC>

caution

If diagnosis code U1102 is set in the engine-ECU, surely perform CAN bus line diagnosis.

caution

Replace ECU after certainly confirming that the communication circuits are normal.

TROUBLE JUDGEMENT

Check Condition

The diagnosis code setting enabled signal is received from ETACS-ECU.

Judgement Criterion

The signals cannot be received from ASTC-ECU for 0.5 second or more.

FAIL-SAFE AND BACKUP FUNCTION

None

COMMENT ON TROUBLE SYMPTOM

Current malfunction

The failure is possibly caused by malfunction of the harness and connector in CAN bus line between engine-ECU and ASTC-ECU, by malfunction in the power supply system of ASTC-ECU, in ASTC-ECU itself, in engine-ECU.

Past malfunction

Proceed with troubleshooting focusing on malfunction of the harness and connector in CAN bus line between engine-ECU and ASTC-ECU and malfunction in the power supply system of ASTC-ECU. For diagnosis procedure, refer to how to cope with past malfunctions (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Treat Past Trouble).

note

In the case of past malfunctions, M.U.T.-III CAN bus line diagnosis cannot detect a malfunction even if there is a malfunction in CAN bus. Therefore, check CAN bus line as in the case of response to intermittent malfunctions (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions). It is possible to narrow down areas with a high possibility of malfunctions from diagnosis codes set in each ECU that performs CAN communication (Refer to GROUP 54C - Explanation about the M.U.T.-III CAN Bus Diagnostics).

PROBABLE CAUSE

Failed of the harness and the connector
Failed engine-ECU
Failed ASTC-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.

	Correct 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

Confirm whether the diagnosis codes are set in the ASTC-ECU.

Q. Is the diagnosis code set?

	YES : Perform the troubleshooting of ASTC system (Refer to GROUP 35C - Troubleshooting - Diagnosis Code Chart ).

	Go to Step 3.

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

Check that the other ECU performing CAN communication with ASTC-ECU sets diagnosis code No. U1102 (Refer to GROUP 54C - CAN communication-related Diagnosis Code Table

Q. Is the diagnosis code set?

	Go to Step 4.

	Go to Step 5.

STEP 4. M.U.T.-III diagnosis code

Reconfirm whether the diagnosis codes are set in the engine-ECU.

Erase the diagnosis codes being set.
Ignition switch: "LOCK" (OFF) to ON
Confirm whether the diagnosis codes are set.

Q. Is the diagnosis code set?

	Go to Step 5.

	Intermittent malfunction in CAN bus line between engine-ECU and ASTC-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction).

STEP 5. Replace the ASTC-ECU

After replacing the ASTC-ECU, re-check whether the diagnosis code is set.

Q. Is the diagnosis code set?

	Replace the engine-ECU.

	The check is end.