GSIC - Global Service Information Center

### DTC P0504/51 Brake Switch "A" / "B" Correlation

## for Preparation Click here

## DESCRIPTION

The signals of the stop light switch's duplex system (STP and ST1-) are used to judge whether the brake system is abnormal or not. When the signals of depressing and releasing the brake pedal are detected simultaneously, the ECM interprets this as a malfunction of the stop light switch.

HINT:

  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

P0504/51

Conditions (1), (2) and (3) continue for 0.5 seconds or more:

1. Ignition switch is ON
2. Brake pedal is released
3. STP signal is OFF when ST1- signal is OFF

1. Short in stop light switch signal circuit
2. Stop light switch
3. ECM

## WIRING DIAGRAM

## INSPECTION PROCEDURE

HINT:

  Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

NOTICE:

  If the ECM is replaced, the new ECM needs initialization (Click here).

## When using intelligent tester:

1.CHECK STOP LIGHT (OPERATION)

1. Check if the stop lights turn ON and OFF normally when the brake pedal is depressed and released.

   OK:
     Stop lights turn ON and OFF when brake pedal is depressed and released.

| NG |

REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT

OK |

2.READ DATA LIST (STP SIGNAL, ST1 - VOLTAGE)

1. Connect the intelligent tester to the DLC3.

1. Turn the ignition switch ON and turn the intelligent tester ON.

1. Enter the following menus: Powertrain / Engine / Data List / Stop Light Switch.

1. Check the result.

   OK:

     Brake Pedal | Specified Condition
     Depressed | STP signal ON
     Released | STP signal OFF

1. Measure the voltage of the ECM connectors.

   Standard voltage:

     Tester Connection | Brake Pedal | Specified Condition
     E6-14 (ST1-) - E7-7 (E1) | Depressed | Below 1.5 V
     E6-14 (ST1-) - E7-7 (E1) | Released | 7.5 to 14 V

| OK |

CHECK FOR INTERMITTENT PROBLEMS

NG |

3.INSPECT STOP LIGHT SWITCH ASSEMBLY

1. Remove the stop light switch.

1. Measure the resistance of the switch.

   Standard resistance:

     Tester Connection | Switch Condition | Specified Condition
     1 - 2 | Pin not pushed | Below 1 Ω
     3 - 4 | Pin not pushed | 10 kΩ or higher
     1 - 2 | Pin pushed | 10 kΩ or higher
     3 - 4 | Pin pushed | Below 1 Ω

| NG |

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK |

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

1. Disconnect the S14 stop light switch connector.

1. Disconnect the E6 ECM connector.

1. Measure the resistance of the wire harness side connector.

   Standard:

     Tester Connection | Specified Condition
     S14-1 - E6-15 (STP) | Below 1 Ω
     S14-4 - E6-14 (ST1-) | Below 1 Ω
     S14-1 or E6-15 (STP) - Body ground | 10 kΩ or higher
     S14-4 or E6-14 (ST1-) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM

## When not using intelligent tester:

1.CHECK STOP LIGHT (OPERATION)

1. Check if the stop lights turn ON and OFF normally when the brake pedal is depressed and released.

   OK:
     Stop lights turn ON and OFF when brake pedal is depressed and released.

| NG |

REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT

OK |

2.CHECK ECM (STP, ST1- VOLTAGE)

1. Turn the ignition switch ON.

1. Measure the voltage of the ECM connectors.

   Standard voltage:

     Tester Connection | Brake Pedal Condition | Specified Condition
     E6-15 (STP) - E7-7 (E1) | Depressed | 7.5 to 14 V
     E6-15 (STP) - E7-7 (E1) | Released | Below 1.5 V
     E6-14 (ST1-) - E7-7 (E1) | Depressed | Below 1.5 V
     E6-14 (ST1-) - E7-7 (E1) | Released | 7.5 to 14 V

| OK |

CHECK FOR INTERMITTENT PROBLEMS

NG |

3.INSPECT STOP LIGHT SWITCH ASSEMBLY

1. Remove the stop light switch.

1. Measure the resistance of the switch.

   Standard:

     Tester Connection | Switch Condition | Specified Condition
     1 - 2 | Pin not pushed | Below 1 Ω
     3 - 4 | Pin not pushed | 10 kΩ or higher
     1 - 2 | Pin pushed | 10 kΩ or higher
     3 - 4 | Pin pushed | Below 1 Ω

| NG |

REPLACE STOP LIGHT SWITCH ASSEMBLY

OK |

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

1. Disconnect the S14 switch connector.

1. Disconnect the E6 ECM connector.

1. Measure the resistance of the wire harness side connector.

   Standard resistance:

     Tester Connection | Specified Condition
     S14-1 - E6-15 (STP) | Below 1 Ω
     S14-4 - E6-14 (ST1-) | Below 1 Ω
     S14-1 or E6-15 (STP) - Body ground | 10 kΩ or higher
     S14-4 or E6-14 (ST1-) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM