Electrical Power Steering System (EPS)

DTC U0415 Vehicle speed (CAN message) data input malfunction

CAUTION:

- If there is any problem in the CAN bus lines, an incorrect DTC may be set. Prior to this diagnosis, diagnose the CAN bus lines Scan Tool Testing and Procedures).

- Whenever ECU is replaced, ensure that the CAN bus lines are normal.

OPERATION

- Electric power steering-ECU receives vehicle speed signal from the ABS-ECU [vehicles with ABS], ASC-ECU [vehicles with ASC].

FUNCTION

- The vehicle speed signal is sent to the electric power steering-ECU for motor control.

TROUBLE JUDGMENT

Check Conditions

- The power supply circuit system DTC C1540, C1541 is not set.

- The DTC related to ABS circuit system [vehicles with ABS]
and ASC circuit system [vehicles with ASC]
is not set.

- The engine circuit system DTC is not set.

Judgment Criterion

- Abnormal vehicle speed signal sent to the electric power steering-ECU is received once or more.

- Abnormal vehicle speed signals are sent from the ABS-ECU [vehicles with ABS], ASC-ECU [vehicles with ASC], and engine control module (ECM), and the microcomputer determines that there is a problem in the vehicle speed measurement system.

Fail Safe, Back Up Function

- The electric power steering-ECU illuminates the electric power steering warning display, and sets the DTC U0415 to limit assist operation.

PROBABLE CAUSES

- Malfunction of CAN bus line

- Malfunction of the electric power steering-ECU

- Malfunction of the engine control module (ECM)

- Malfunction of the ABS-ECU [vehicles with ABS]

- Malfunction of the ASC-ECU [vehicles with ASC]

DIAGNOSIS

Required Special Tools:

- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: Vehicle Communication Interface (V.C.I.)

- MB991827: M.U.T.-III USB Cable

- MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)

STEP 1. Using scan tool MB991958, diagnose the CAN bus lines.

Use scan tool to diagnose the CAN bus lines.

Q. Is the check result normal?

YES Go to Step 3.
NO Repair the CAN bus lines CAN Bus Diagnostics Chart). On completion, go to Step 2.
STEP 2. DTC recheck after resetting CAN bus lines

(1)Erase the DTC.

(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the DTC is set.

Q. Is the DTC U0415 set?

YES Go to Step 3.
NO This diagnosis is complete.
STEP 3. Using scan tool MB991958, check the data list

Check the following data list Data List Reference Table.

- Item No. 08: Vehicle speed

Q. Is the check result normal?

YES Go to Step 5.
NO Perform troubleshooting for ABS-ECU Anti-Lock Braking System (ABS) [vehicles with ABS]), ASC-ECU
Active Stability Control System (ASC) [vehicles with ASC]). Then go to Step 4.
STEP 4. Check whether the DTC is reset

(1)Erase the DTC.

(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the DTC is set.

Q. Is the DTC U0415 set?

YES Replace the electric power steering-ECU (Refer to Service and Repair).Then go to Step 5.
NO Intermittent malfunction How to Cope With Intermittent Malfunctions).
STEP 5. Check whether the DTC is reset.

(1)Erase the DTC.

(2)Turn the ignition switch from the "LOCK" (OFF) position to the "ON" position.

(3)Check if the DTC is set.

Q. Is the DTC U0415 set?

YES Return to Step 1.
NO This diagnosis is complete.