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


caution If diagnosis code U1004 is set from engine-ECU, surely perform CAN busline diagnosis.
caution Replace ECU after certainly confirming that the communication circuits are normal.

TROUBLE JUDGMENT


Check Conditions
  • After 4 seconds have passed since the ignition switch was turned to "ON" position.
  • Battery positive voltage is more than 11 V and is less than 16.5 V.
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 busline 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 busline 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 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 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



  • The auto stop is prohibited.

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 busline diagnosis.

Q. Is the check result normal?
Go to Step 2 .
Repair CAN busline (Refer to GROUP 54C - Troubleshooting - CAN Bus Diagnostics Table ). After repairing CAN busline, go to Step 6 .

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

  • Confirm the diagnosis code is set from the AS&G-ECU.

Q. Is diagnosis code set?
Perform troubleshooting of AS&G system (Refer to GROUP 17 - Auto Stop & Go (AS&G) System - Diagnosis Code Chart ).
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 Communication-related Diagnosis Code (U-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 the diagnosis code is set from the engine-ECU.

  1. Erase the set diagnosis code.
  2. Ignition switch: LOCK (OFF) → ON
  3. 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 busline 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 the diagnosis code is set from the engine-ECU.

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

Q. Is diagnosis code set?
Replace engine-ECU, go to Step 6 .
Intermittent malfunction in CAN busline 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 the diagnosis code is set from the engine-ECU.

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

Q. Is diagnosis code set?
Go to Step 1 .
Check end.