ECD SYSTEM, Diagnostic DTC:P1520

DTC Code DTC Name
P1520 Stop Light Switch Circuit

DESCRIPTION

In this system, the signal of the stop light switch is used to judge whether the stop light system is abnormal or not.

The stop light switch has a duplex system (signals STP and ST1-) to memorize the abnormality when the signals of depressing and releasing the brake pedal are detected simultaneously.

Tech Tips

Normal condition is as shown in the table.

Signal Brake pedal released In transition Brake pedal depressed
STP OFF ON ON
ST1- ON ON OFF
DTC No. DTC Detection Condition Trouble Area
P1520 When STP (without depressing the brake pedal) and ST1- (with the brake pedal depressed) signals continue for longer than 0.5 seconds with the ignition switch ON.

  • Open or short in stop light switch signal circuit

  • Stop light switch assembly

  • ECM

WIRING DIAGRAM

B007VGSE03

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following inspection procedure.

Tech Tips

Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK STOP LAMP SWITCH ASSEMBLY (TERMINAL B VOLTAGE)


    1. B007P03E14
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      B2-2 - Body ground Always 11 to 14 V
      B2-4 - Body ground Ignition switch ON 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LAMP SWITCH ASSEMBLY


    1. B007SQOE02

      Disconnect the stop light switch assembly connector.

    2. Check the resistance between each pair of the terminals.

      Standard Resistance
      Switch Position Tester Connection Specified Condition
      Switch pin free 1 - 2 Below 1 Ω
      Switch pin pushed in 1 - 2 10 kΩ or higher
      Switch pin free 3 - 4 10 kΩ or higher
      Switch pin pushed in 3 - 4 Below 1 Ω

    NG

    REPLACE STOP LAMP SWITCH ASSEMBLY

    OK

  3. INSPECT ECM (STP AND ST1- VOLTAGE)

    B007V2YE14
    Text in Illustration
    *a Brake Pedal Depressed
    *b Brake Pedal Released
    *c

    Front view of wire harness connector

    (to ECM)

    1. Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Brake Pedal Condition Specified Condition
      B74-26 (ST1-) - Body ground Released 11 to 14 V
      Depressed Below 1.5 V
      B74-27 (STP) - Body ground Released Below 1.5 V
      Depressed 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here