Code No.U1073: Bus-off

caution

If diagnosis code U1073 is set in the ASTC-ECU, always diagnose the CAN main bus line. 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 JUDGEMENT

This code is stored when the ASTC-ECU has ceased the CAN communication (bus off). Then, if a penalty mode is entered after approximately five minutes, regular data transmission will be cancelled.

PROBABLE CAUSES

Damaged wiring harness or connector

Malfunction of the hydraulic unit (integrated with ASTC-ECU)

DIAGNOSIS PROCEDURE

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

Use M.U.T.-III to diagnose the CAN bus lines.

Q. Is the check result normal?

	Go to Step 2.

	Repair the CAN bus lines (Refer to GROUP 54C - CAN Bus Diagnostics Table ). Then go to Step 2.

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

(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.

Q. Is code No.U1073 set?

	Replace the hydraulic unit (integrated with ASTC-ECU) (Refer to ). Then go to Step 3.

	Intermittent malfunction (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).

STEP 3. Check whether the diagnosis code is reset.