GSIC - Global Service Information Center

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

## for Preparation Click here

## DESCRIPTION

In this system, the signal of the stop light switch is used to judge whether the acceleration 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.

HINT:

  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

P0504

1. Conditions (a), (b) and (c) continue for 0.5 sec 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:

  Reed 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, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

1.CHECK OPERATION OF STOP LIGHT

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

   OK:
     Stop lights illuminate and turn off.

| NG |

REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT

OK |

2.INSPECT STOP LIGHT SWITCH

1. Measure the resistance of the switch.

   Standard resistance:

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

| NG |

REPLACE STOP LIGHT SWITCH

OK |

3.READ DATA LIST (STP SIGNAL AND ST1 - VOLTAGE)

1. Connect the intelligent tester to the DLC3.

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

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

1. Check the result.

   Standard:

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

1. Measure the voltage of the E14 and E17 ECM connectors.

   Standard voltage:

     Tester Connection | Brake Pedal | Specified Condition
     E14-16 (ST1-) - E17-1 (E1) | Depressed | Below 1.5 V
     E14-16 (ST1-) - E17-1 (E1) | Released | 7.5 to 14 V

| OK |

CHECK FOR INTERMITTENT PROBLEMS

NG |

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

1. Disconnect the S14 stop light switch connector.

1. Disconnect the E14 ECM connector.

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

   Standard resistance:

     Tester Connection | Specified Condition
     S14-1 - E14-15 (STP) | Below 1 Ω
     S14-4 - E14-16 (ST1-) | Below 1 Ω
     S14-1 or E14-15 (STP) - Body ground | 10 kΩ or higher
     S14-4 or E14-16 (ST1-) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPLACE ECM