When three minutes
or more elapse since the electric motor switch is turned ON, the EPS-ECU may set diagnosis codes
No. U1100, U1102, U1108, and U1109, and M.U.T.-III may show the diagnosis code status as the historic
trouble.
If the EPS-ECU sets the diagnosis code No. U1102, diagnose the CAN bus lines. If
there is any fault in the CAN bus lines, an incorrect diagnosis code may be set.
Before replacing ECU, ensure that the communication circuit is normal.
TROUBLE JUDGEMENT
EPS-ECU receives the vehicle speed data (wheel speed sensor data) from the ASC-ECU via
CAN bus lines. If the EPS-ECU cannot receive the vehicle speed data (wheel speed sensor data)
from the ASC-ECU, the diagnosis code No. U1102 will be set.
COMMENT ON TROUBLE SYMPTOM
Current trouble
The wiring harness or connector in the CAN bus lines between the EPS-ECU and ABS-ECU,
the power supply system of the ASC-ECU, or the EPS-ECU itself may be defective.
Past trouble
If the diagnosis code No. U1102 is stored as a historic trouble, carry out the diagnosis
with particular emphasis on the wiring harness and connector in the CAN bus lines between the EPS-ECU
and ABS-ECU as well as on the power supply system of the ASC-ECU. For diagnosis procedures,
refer to "How to treat past trouble" (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points ).
note
In case of a historic trouble, the M.U.T.-III CAN bus diagnosis cannot find the problem
even when there is an abnormality in the CAN bus. In this case, be sure to diagnose the CAN
bus lines in the same manner as for "How to Cope with Intermittent Malfunction" (refer to GROUP
00 - How to Use Troubleshooting/Inspection Service Points ).
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 - Explanation
About the M.U.T.-III CAN Bus Diagnostics ).
PROBABLE CAUSES
Defective harness wire(s) or connector(s)
Malfunction of the ASC-ECU.
Malfunction of the EPS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnosis
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 lines. (Refer to GROUP 54C, Troubleshooting .
) After repairing the CAN bus lines, go to STEP 2.
STEP 2. Use M.U.T.-III to confirm a diagnosis code of other systems.
Check that the ABS-ECU sets a diagnosis code.
Q.
Is the diagnosis code set?
Perform the troubleshooting for the ASC. Refer to .
Go to Step 3.
STEP 3. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Start the electric motor unit.
(3)Check if the diagnosis code No. U1102 is set as a current trouble.
Q.
Is diagnosis code U1102 set?
Replace the EPS-ECU (refer to ), and then go
to Step 4.
Go to Step 4.
STEP 4. Diagnosis code recheck
Recheck if the diagnosis code is set.
(1)Turn the electric motor switch to the "LOCK" (OFF) → "ON" position.
(2)Check if the diagnosis code No. U1102 is set as a current trouble.
Q.
Is diagnosis code U1102 set?
Replace the hydraulic unit (integrated with ASC-ECU).
).
