ECD SYSTEM, Diagnostic DTC:51

DTC Code DTC Name
51 Stop Light Switch Circuit Malfunction

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

The normal condition is shown in the table below.

Signal Brake pedal released In transition Brake pedal depressed
STP OFF ON ON
ST1- ON ON OFF
DTC No. DTC Detection Condition Trouble Area
51 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

  • ECM

WIRING DIAGRAM

A01DZIQE01

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

When using intelligent tester:

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch ON.

    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light SW.

      OK
      Brake Pedal Display
      Depressed Stop Light SW ON
      Repressed Stop Light SW OFF

    OK

    CHECK FOR INTERMITTENT PROBLEMS

    NG

  2. CHECK ECM (STP, ST1- VOLTAGE)


    1. A01DVE2E03

      Turn the ignition switch ON.

    2. Measure the voltage of the ECM connector.

      Standard voltage
      Brake pedal is depressed
      Tester Connection Specified Condition
      E20-19 (STP) - E23-14 (E1) 9 to 14 V
      E21-11 (ST1-) - E23-14 (E1) Below 1.5 V
      Standard voltage
      Brake pedal is released
      Tester Connection Specified Condition
      E20-19 (STP) - E23-14 (E1) Below 1.5 V
      E21-11 (ST1-) - E23-14 (E1) 9 to 14 V

    OK

    REPLACE ECM

    NG

  3. INSPECT STOP LIGHT SWITCH


    1. A01DXWSE06

      Disconnect the stop light switch connector.

    2. Measure the resistance of the sensor.

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

    NG

    REPLACE STOP LIGHT SWITCH

    OK

  4. CHECK WIRE HARNESS (ECM - STOP LIGHT SWITCH)


    1. A01DVUOE03

      Disconnect the S14 stop light switch connector.

    2. Disconnect the E20 and E21 ECM connectors.

    3. Measure the resistance of the wire harness side connectors.

      Standard resistance
      Tester Connection Specified Condition
      S14-1 - E20-19 (STP) Below 1 Ω
      S14-4 - E21-11 (ST1-) Below 1 Ω
      E20-19 (STP) - Body ground 10 kΩ or higher
      E21-11 (ST1-) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPAIR OR REPLACE POWER SOURCE CIRCUIT

When not using intelligent tester:

PROCEDURE


  1. CHECK STOP LIGHT (OPERATION)


    1. Check if the stop lights go on and off normally when the brake pedal is depressed and released.

      OK
      The stop lights go on and off normally.

    NG

    REPAIR STOP LIGHT SWITCH CIRCUIT

    OK

  2. CHECK ECM (STP, ST1- VOLTAGE)


    1. A01DVE2E03

      Turn the ignition switch ON.

    2. Measure the voltage of the ECM connector.

      Standard voltage
      Brake pedal is depressed
      Tester Connection Specified Condition
      E20-19 (STP) - E23-14 (E1) 9 to 14 V
      E21-11 (ST1-) - E23-14 (E1) Below 1.5 V
      Standard voltage
      Brake pedal is released
      Tester Connection Specified Condition
      E20-19 (STP) - E23-14 (E1) Below 1.5 V
      E21-11 (ST1-) - E23-14 (E1) 9 to 14 V

    OK

    REPLACE ECM

    NG

  3. INSPECT STOP LIGHT SWITCH


    1. A01DXWSE06

      Disconnect the stop light switch connector.

    2. Measure the resistance of the sensor.

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

    NG

    REPLACE STOP LIGHT SWITCH

    OK

  4. CHECK WIRE HARNESS (ECM - STOP LIGHT SWITCH)


    1. A01DVUOE03

      Disconnect the S14 stop light switch connector.

    2. Disconnect the E20 and E21 ECM connectors.

    3. Measure the resistance of the wire harness side connectors.

      Standard resistance
      Tester Connection Specified Condition
      S14-1 - E20-19 (STP) Below 1 Ω
      S14-4 - E21-11 (ST1-) Below 1 Ω
      E20-19 (STP) - Body ground 10 kΩ or higher
      E21-11 (ST1-) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPAIR OR REPLACE POWER SOURCE CIRCUIT