Code No. U1101: A/T-ECU Time-out <A/T>

caution

If Diagnosis Code U1101 is output from engine-ECU surely perform CAN busline diagnosis.

caution

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

note

When the diagnosis codes relating to the CAN communication error are output, make sure of the vehicle equipment. When the vehicle is not equipped with the system the engine-ECU communicates to, the diagnosis code is always output. This is not abnormal.

TROUBLE JUDGMENT

Check Condition

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

Judgment Criterion

The signals cannot be received from A/T-ECU for 65 seconds or more.

COMMENT ON TROUBLE SYMPTOM

Current malfunction

The failure is possibly caused by malfunction of the harness and connector in CAN busline between engine-ECU and A/T-ECU, by malfunction in the power supply system of A/T-ECU, in combination meter itself, in engine-ECU.

Past malfunction

Proceed with troubleshooting focusing on malfunction of the harness and connector in CAN busline between engine-ECU and A/T-ECU and malfunction in the power supply system of A/T-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 Malfunctions

note

In the case of past malfunctions, M.U.T.-III CAN busline diagnosis cannot detect a malfunction even if there is a malfunction in CAN bus. Therefore, check CAN busline 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 output to each ECU that performs CAN communication (Refer to GROUP 54D - Explanation about the M.U.T.-III CAN Bus Diagnostics

PROBABLE CAUSES

Failed of the harness and the connector
Failed A/T-ECU
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Using M.U.T.-III, perform CAN busline diagnosis.

Q. Is the check result normal?

	Go to Step 2 .

	Correct CAN busline (Refer to GROUP 54D - Troubleshooting - CAN Bus Diagnosis Table ), and then go to Step 6 .

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

Confirm whether the diagnosis codes are output from A/T-ECU.

Q. Is the diagnosis code set?

	Perform the troubleshooting of A/T-ECU (Refer to GROUP 23A - Troubleshooting <A/T> - Diagnosis Code chart ).

	NO : Go to Step 3 .

STEP 3. M.U.T.-III other system diagnosis codes.

Confirm whether Diagnosis Code U1101: A/T-ECU time out is output from the following ECU having CAN communication with automatic transmission.

Combination meter

Q. Is the diagnosis code set?

	Go to Step 4 .

	Go to Step 5 .

STEP 4. Reconfirmation of diagnosis codes

Reconfirm whether the diagnosis codes are output from engine-ECU

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

Q. Is the diagnosis code set?

	After replacing the A/T-ECU, go to Step 6 .

	Intermittent malfunction in CAN busline between engine-ECU and A/T-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 5. Reconfirmation of diagnosis codes

Reconfirm whether the diagnosis codes are output from engine-ECU

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

Q. Is the diagnosis code set?

Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing

). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns

). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration

), and then go to Step 6 .

	Intermittent malfunction in CAN busline between engine-ECU and A/T-ECU (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Reconfirmation of diagnosis codes

Reconfirm whether the diagnosis codes are output from engine-ECU

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

Q. Is the diagnosis code set?

	Go to Step 1 .

	The check is end.