If the diagnosis
code No. U1000 is set, diagnose the CAN bus lines.
When replacing the ECU, always check that the communication circuit is normal.
DIAGNOSIS FUNCTION
When the signal from OSS-ECU cannot be received, KOS-ECU sets the diagnosis code No.U1000.
PROBABLE CAUSES
Malfunction of CAN bus line
Malfunction of OSS-ECU
Malfunction of KOS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use 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 2.
STEP 2. Check the M.U.T.-III Diagnosis code for other systems
Check that the OSS-ECU set a diagnosis code.
Q.
Is the diagnosis code set?
Diagnose the OSS-ECU. Refer to Troubleshooting .
Go to Step 3
STEP 3. M.U.T.-III other system diagnosis code
Check if diagnosis code No.U1000 is set to the ETACS-ECU.
Q.
Is the diagnosis code set?
Go to Step 4.
Go to Step 5.
STEP 4. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the power supply mode of the engine switch from OFF to ON.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace the OSS-ECU.
Intermittent malfunction is suspected (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunction ).
STEP 5. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Erase the diagnosis code.
(2)Turn the power supply mode of the engine switch from OFF to ON.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace KOS-ECU and register the ID codes (Refer to ).
Intermittent malfunction is suspected (Refer to GROUP 00 -
How to Use Troubleshooting/Inspection
Service Points -
How to Cope with Intermittent Malfunction ).