Code No.U1102:
ASTC-ECU timeout
| caution |
- If diagnosis
code No.U1102 is set in the ETACS-ECU, diagnose the CAN main bus line.
- Whenever the ECU is replaced, ensure that the input and output signal circuits are normal.
- For vehicles without ASTC, diagnosis code No. U1110 does not mean that there is
a problem.
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| note |
When the diagnosis codes relating to the CAN communication error are set, make sure of
the vehicle equipment. When the vehicle is not equipped with the system the ETACS-ECU communicates
to, the diagnosis code is always output. This is not abnormal.
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TROUBLE JUDGEMENT
The ETACS-ECU receives signal from the ASTC-ECU. If ASTC-related signal cannot be received
at all, diagnosis code No.U1102 will be set.
COMMENT ON TROUBLE SYMPTOM
The M.U.T.-III shows a diagnosis code status as active.
- Connector(s) or wiring harness in the CAN bus lines between the ASTC-ECU and the
ETACS-ECU, the power supply system to the ASTC-ECU, the ASTC-ECU itself, or the ETACS-ECU may
be defective.
The M.U.T.-III shows a diagnosis code status as stored.
- If diagnosis code No.U1102 is stored as a past trouble, carry out diagnosis with
particular emphasis on wiring and connector(s) in the CAN bus line between the ASTC-ECU and
the ETACS-ECU, and the power supply system to the ASTC-ECU. For diagnosis procedures, refer
to GROUP 00, How to Use Troubleshooting/Inspection Service Points -
How to
Treat Past Trouble
.
| note |
For a past trouble, you cannot find it by the M.U.T.-III CAN bus diagnostics even if there is
any failure in CAN bus lines. In this case, refer to GROUP 00, How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunctions and
check the CAN bus lines. You can narrow down the probable cause of the trouble by referring
to the diagnosis code, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C -
CAN
Bus Line Diagnostic Flow ).
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PROBABLE CAUSES
- Malfunction of the ASTC-ECU
- Damaged harness wires and connectors
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use the M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C -
Troubleshooting ).
On completion, go to Step 6.
STEP 2. Check the diagnosis code of the ASTC.
Check that the ASTC-ECU sets a diagnosis code.
Q.
Is the diagnosis code set?
Diagnose the ASTC-ECU (Refer to GROUP 35C, Troubleshooting ).
On completion, go to Step 6.
Go to Step 3.
STEP 3. M.U.T.-III other system diagnosis code
Check if a diagnosis code, which relates to CAN communication-linked systems below, is
set.
- Engine-ECU
U1102: ASTC-ECU timeout
- A/T-ECU
U1102: ASTC-ECU timeout
Q.
Is the diagnosis code set?
Go to Step 5.
Go to Step 4.
STEP 4. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)On completion, check that the diagnosis code is reset.
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Q.
Is the diagnosis code set?
Replace the ASTC-ECU. Then, carry out the CAN bus diagnostics. Then go to Step 6
.
A poor connection, open circuit or other intermittent malfunction is present in
the CAN bus lines between the ASTC-ECU and the ETACS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunctions ).
STEP 5. Check whether the diagnosis code is reset.
Check again if the diagnosis code is set to the ETACS-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)On completion, check that the diagnosis code is reset.
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Q.
Is the diagnosis code set?
Replace the ETACS-ECU and register the ID codes (Refer to ).
Then, carry out the CAN bus diagnostics. Then go to Step 6 .
A poor connection, open circuit or other intermittent malfunction is present in
the CAN bus lines between the ASTC-ECU and the ETACS-ECU (Refer to GROUP 00, How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunctions ).
STEP 6. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set to the ETACS-ECU.
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(1)Erase the diagnosis code.
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(2)Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
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(3)On completion, check that the diagnosis code is reset.
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Q.
Is the diagnosis code set?
Return to Step 1.
The procedure is complete.