ELECTRONIC POWER STEERING SYSTEM, Diagnostic DTC:C1541/41, C1542/42, C1571/71

DTC Code DTC Name
C1541/41 Speed Sensor Malfunction
C1542/42 Speed Sensor Malfunction
C1571/71 Speed Sensor Malfunction (Test Mode DTC)

DESCRIPTION

Based on the vehicle speed signal received from the combination meter, the power steering ECU adjusts the amount of power assist according to vehicle speed. The power steering ECU monitors the speed signal input and stores a DTC if a malfunction is detected. While a malfunction exists in the vehicle speed signal, fail-safe operation maintains the amount of power assist at the level for a speed of 70 km/h (43 mph).

Note

Revving the engine while the vehicle is stopped may cause DTC C1541/41 or C1542/42 to be stored.

Tech Tips


  • If C1541/41 is stored while the vehicle is stopped, driving the vehicle for 5 minutes or more and then turning the ignition switch off will clear the DTC.

  • If C1542/42 is stored while the vehicle is stopped, driving the vehicle for 5 minutes or more will clear the DTC.

  • When the sensor is normal, a pulse signal (43 Hz at 37 mph [60 km/h]) that alternates between 0 V and 5 V is transmitted to the ECU.

DTC No. Detection Item Trouble Area
C1541/41 Vehicle Speed Signal Abnormal Increase

  • Speed sensor

  • Speed sensor circuit

  • Combination meter

  • Power steering ECU
While vehicle stopped, engine rpm exceeds threshold* for 300 seconds or more, cumulative. -
C1542/42 Vehicle Speed Signal Abnormal Decrease

  • Speed sensor

  • Speed sensor circuit

  • Combination meter

  • Power steering ECU
While vehicle stopped, engine rpm exceeds threshold* for 30 seconds or more, cumulative. -
C1571/71 Speed sensor malfunction (Test mode).

  • Speed sensor

  • Speed sensor circuit

  • Combination meter

  • Power steering ECU

*Threshold: An engine speed of 4000 rpm or greater is detected within 5 minutes after engine is started, or an engine speed of 2100 rpm or greater is detected 5 minutes or more after engine is started.

A01369DE01

WIRING DIAGRAM

A0138PHE02

INSPECTION PROCEDURE

Tech Tips


  • Confirm that DTC C1571/71 has been cleared by activating test mode after the repair is completed.

PROCEDURE


  1. CHECK DTC OUTPUT

    Check whether the DTC for brake control system is output.

    OK
    No DTC for brake control system is output.

    NG

    REPAIR CIRCUIT INDICATED BY OUTPUT DTC

    OK

  2. READ VALUE USING INTELLIGENT TESTER


    1. Turn the ignition switch off.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON.

    4. Turn the tester on.

    5. Enter the following menus: Chassis / EMPS / Data List.

    6. Select the item Meter Vehicle Velocity in the Data List and read the value displayed on the intelligent tester.

    7. Check that there is no significant difference between the speed value output from the speedometer displayed by the intelligent tester and the speed value displayed by the speed meter when driving the vehicle.

      OK
      Speed values are same.
      Result
      Result Proceed to
      NG A
      OK B

      Tech Tips

      There is tolerance of +/-10% in the speed meter indication.


    B

    REPLACE POWER STEERING ECU ASSEMBLY Click here

    A

  3. CHECK HARNESS AND CONNECTOR (POWER STEERING ECU ASSEMBLY - SKID CONTROL ECU)


    1. Disconnect the C23 power steering ECU connector.

    2. Disconnect the A46 skid control ECU connector (w/o VSC).

    3. Disconnect the A41 skid control ECU connector (w/ VSC).

    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      w/o VSC
      Tester Connection Condition Specified Condition
      SPD (C23-5) - SP1 (A46-2) Always Below 1Ω
      SPD (C23-5) or SP1 (A46-2) - Body ground Always 10 kΩ or higher
      Standard Resistance
      w/ VSC
      Tester Connection Condition Specified Condition
      SPD (C23-5) - SP1 (A41-33) Always 19 to 22 Ω
      SPD (C23-5) or SP1 (A41-33) - Body ground Always 10 kΩ or higher

    5. Reconnect the power steering ECU connector.

    6. Reconnect the skid control ECU connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    GO TO BRAKE CONTROL SYSTEM