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

A0136MZE03

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. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch ON, and turn the intelligent tester main switch ON.

    3. Select the item SPD in the DATA LIST and read the value displayed on the intelligent tester.

    4. 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.

      Tech Tips

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


    OK

    REPLACE POWER STEERING ECU ASSEMBLY

    NG

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

    A0138HFE01

    1. Disconnect the skid control ECU connector and power steering ECU connector C23.

    2. Measure the resistance.

      Standard resistance
      w/o VSC
      Tester Connection Specified Condition
      SPD (C23-5) - SP1 (A21-23) Below 1 Ω

      w/ ABS Resistor

      SPD (C23-5) - SP1 (A21-23)

      		 19 to 22 Ω
      SPD (C23-5) or SP1 (A21-23) - Body ground 10 kΩ or higher
      Standard resistance
      w/ VSC
      Tester Connection Specified Condition
      SPD (C23-5) - SP1 (A41-33) Below 1 Ω

      w/ ABS Resistor

      SPD (C23-5) - SP1 (A41-33)

      		 19 to 22 Ω
      SPD (C23-5) or SP1 (A41-33) - Body ground 10 kΩ or higher

    3. Reconnect the connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    GO TO BRAKE CONTROL SYSTEM