Code No. U1004: AS&G-ECU Time-out <Vehicles with AS&G system>

caution

If diagnosis code U1004 is stored in the engine-ECU, surely perform CAN bus line diagnosis.

caution

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

TROUBLE JUDGMENT

Check Conditions

Battery positive voltage is more than 10 V and is less than 16.5 V.
More than 2 seconds have passed since the ignition switch was turned to "ON" position.
After 2 seconds since the battery voltage has reached 10 V or more.

Judgement Criterion

Unable to receive AS&G-ECU signals through the CAN bus line for 4 seconds.

COMMENTS 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 AS&G-ECU, by malfunction in the power supply system of AS&G-ECU, in AS&G-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 AS&G-ECU and malfunction in the power supply system of AS&G-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 to each ECU that performs CAN communication (Refer to GROUP 54C - Explanation about the M.U.T.-III CAN Bus Diagnostics

FAIL-SAFE AND BACKUP FUNCTION

Disables idling stop.

PROBABLE CAUSES

Failed harness and connector
Failed AS&G-ECU
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Use M.U.T.-III to perform CAN bus line diagnosis.

Q. Is the check result normal?

	Go to Step 2.

	Repair CAN bus line (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnostics Table ). After repairing CAN bus line, go to Step 6 .

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

Confirm whether the diagnosis code is stored in the AS&G-ECU.

Q. Is diagnosis code set?

	Perform troubleshooting of AS&G system (Refer to GROUP 17 - Auto Stop & Go System - Diagnosis Code Chart <M/T>, <CVT>).

	Go to Step 3.

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

Check that the other ECU performing CAN communication with AS&G-ECU sets diagnosis code No. U1004 [Refer to GROUP 54C - CAN-related Diagnosis Code Table

Q. Is diagnosis code set?

	Go to Step 4.

	Go to Step 5.

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

Reconfirmation of diagnosis code.

Confirm again whether the diagnosis code is stored in the engine-ECU.

Erase the set diagnosis code.
Ignition switch: LOCK (OFF) → ON
Confirm whether the diagnosis code is set.

Q. Is diagnosis code set?

	After replacing AS&G-ECU, go to Step 6.

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

STEP 5. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Confirm again whether the diagnosis code is stored in the engine-ECU.

Erase the set diagnosis code.
Ignition switch: LOCK (OFF) → ON
Confirm whether the diagnosis code is set.

Q. Is diagnosis code set?

	Replace engine-ECU, go to Step 6.

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

STEP 6. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Confirm again whether the diagnosis code is stored in the engine-ECU.

Erase the set diagnosis code.
Ignition switch: LOCK (OFF) → ON
Confirm whether the diagnosis code is set.

Q. Is diagnosis code set?

	Go to Step 1.

	Check end.