Code No. U1000:
OSS/KOS_OSS CAN timeout
caution |
If diagnosis code No.U1000 is set in the auto A/C controller
assembly (A/C-ECU), diagnose the CAN main bus line.
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caution |
Whenever the ECU is replaced, ensure that the communication
circuit is normal.
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The auto A/C controller assembly (A/C-ECU) receives air conditioner control-related signals
from the KOS&OSS-ECU via the CAN bus lines. If the ECU cannot receive any of the air conditioner
control-related signals from the KOS&OSS-ECU, diagnosis code U1000 will be set.
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COMMENTS ON TROUBLE SYMPTOM
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Current trouble
- Connector(s) or wiring harness in the CAN bus lines between the KOS&OSS-ECU
and the auto A/C controller assembly (A/C-ECU), the power supply system to the OSS, the KOS&OSS-ECU
itself, or the auto A/C controller assembly (A/C-ECU) may be faulty.
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Past trouble
- Carry out diagnosis with particular emphasis on connector(s) or wiring harness in
the CAN bus lines between the auto A/C controller assembly (A/C-ECU) and the KOS&OSS-ECU,
and the power supply system to the OSS. For diagnosis procedures, refer to "How to treat past trouble"
(Refer to GROUP 00 - How to Treat Past Trouble
).
note |
For a past trouble, you can not 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 Cope with Intermittent
Malfunction and check the CAN bus lines. You can narrow down
the possible 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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caution |
If the ignition switch is turned to the ON position without starting
the engine, the diagnosis code U1000 (past trouble) may be set to the auto A/C controller assembly
(A/C-ECU) after three minutes.
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- Damaged wiring harness or connectors
- Malfunction of the KOS&OSS-ECU
- Malfunction of the auto A/C controller assembly (A/C-ECU)
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STEP 1. M.U.T.-III CAN bus diagnostics
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Use the M.U.T.-III to diagnose the CAN bus lines.
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Q.
Is the check result normal?
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Go to Step 2.
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Repair the CAN bus lines (Refer to GROUP 54C Troubleshooting ).
On completion, go to Step 6.
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STEP 2. M.U.T.-III other system diagnosis code
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Check whether the KOS&OSS-ECU-related diagnosis code is set.
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Q.
Is the diagnosis code set?
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Diagnose the KOS&OSS-ECU (Refer to GROUP 42B Troubleshooting ).
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Go to Step 3.
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STEP 3. M.U.T.-III other system diagnosis code
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Check if a diagnosis code, which relates to CAN communication-linked systems below, is
set.
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- ETACS-ECU
U1000: OSS/KOS_OSS CAN timeout
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Q.
Is the diagnosis code set?
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Go to Step 4.
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Go to Step 5.
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STEP 4. Check whether the diagnosis code is set again.
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Recheck if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: "LOCK" (OFF) to "ON"
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
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Replace the KOS&OSS-ECU, and then go to Step 6.
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A poor connection, open circuit or other intermittent malfunction in the CAN bus
line between the KOS&OSS-ECU and auto A/C controller assembly (A/C-ECU) (Refer to GROUP
00 - How to Cope with Intermittent Malfunction ).
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STEP 5. Check whether the diagnosis code is set again.
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Recheck if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: "LOCK" (OFF) to "ON"
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
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Replace the auto A/C controller assembly (A/C-ECU), and then go to Step 6.
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A poor connection, open circuit or other intermittent malfunction in the CAN bus
line between the KOS&OSS-ECU and the auto A/C controller assembly (A/C-ECU) (Refer
to GROUP 00 - How to Cope with Intermittent Malfunction ).
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STEP 6. Check whether the diagnosis code is set again.
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Recheck if the diagnosis code is set.
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(1)Erase the diagnosis code.
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(2)Ignition switch: "LOCK" (OFF) to "ON"
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(3)Check if the diagnosis code is set.
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Q.
Is the diagnosis code set?
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Return to Step 1.
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The procedure is complete.
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