GSIC - Global Service Information Center

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

## for Preparation Click here

## DESCRIPTION

In this system, 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.

Signal | Brake Pedal Released | In Transition | Brake Pedal Depressed
STP | OFF | ON | ON
ST1- | ON | ON | OFF

HINT:

  The normal condition of the signals is shown in the table above.

DTC No. | DTC Detection Condition | Trouble Area

P0504/51

Conditions (a), (b) and (c) continue for 0.5 seconds or more:

1. (a) Ignition switch ON
2. (b) Brake pedal released
3. (c) STP signal is OFF when ST1- signal is OFF

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

## WIRING DIAGRAM

## INSPECTION PROCEDURE

HINT:

  Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions 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, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

## When using intelligent tester:

1.CHECK STOP LIGHT (OPERATION)

1. Check that the stop lights turn ON and OFF when the brake pedal is depressed and released, respectively.

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

| 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 and ECT / Data List / Stop Light Switch.

1. Check the STP signal when depressing and releasing the brake pedal.

   OK:

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

1. Measure the voltage of the ECM connectors.

   Standard voltage:

     Tester Connection | Brake Pedal Condition | Specified Condition
     E9-16 (ST1-) - E12-3 (E1) | Depressed | Below 1.5 V
     E9-16 (ST1-) - E12-3 (E1) | Released | 7.5 to 14 V

| OK |

CHECK FOR INTERMITTENT PROBLEMS

NG |

3.INSPECT STOP LIGHT SWITCH ASSEMBLY

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 ECM (STOP LIGHT SWITCH - ECM)

1. Disconnect the E9 and E10 ECM connectors.

1. Disconnect the S14 stop light switch connector.

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

   Standard resistance:

     Tester Connection | Specified Condition
     S14-1 - E10-4 (STP) | Below 1 Ω
     S14-4 - E9-16 (ST1-) | Below 1 Ω

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM

## When not using intelligent tester:

1.CHECK STOP LIGHT (OPERATION)

1. Check that the stop lights turn ON and OFF when the brake pedal is depressed and released, respectively.

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

| 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
     E10-4 (STP) - E12-3 (E1) | Depressed | 7.5 to 14 V
     E10-4 (STP) - E12-3 (E1) | Released | Below 1.5 V
     E9-16 (ST1-) - E12-3 (E1) | Depressed | Below 1.5 V
     E9-16 (ST1-) - E12-3 (E1) | Released | 7.5 to 14 V

| OK |

CHECK FOR INTERMITTENT PROBLEMS

NG |

3.INSPECT STOP LIGHT SWITCH ASSEMBLY

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 ECM (STOP LIGHT SWITCH - ECM)

1. Disconnect the E9 and E10 ECM connectors.

1. Disconnect the S14 stop light switch connector.

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

   Standard resistance:

     Tester Connection | Specified Condition
     S14-1 - E10-4 (STP) | Below 1 Ω
     S14-4 - E9-16 (ST1-) | Below 1 Ω

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM