Kia Forte BD Quiz
Brake System

Stop Lamp Switch

In this manual: Brake System
General Information — 8Maintenance — 32Engine Mechanical System — 47Engine Electrical System — 17Emission Control System — 10Engine Control System/Fuel System — 32Clutch System — 11Manual Transmission — 11DCT (Dual Clutch Transmission) System — 16Drive Shaft and Axle — 8Suspension System — 26Steering — 9Restraints — 11Brake System — 27Body (Interior and Exterior) — 119Body Electrical System — 98Heating, Ventilation, and Air Conditioning — 27
22steps
~132min
4/5difficulty
Done 0 of 22

Components and Component Location

Components

1. Brake Pedal Assembly
2. Stop Lamp Switch		 3. Brake Pedal Lever

Description and Operation

Operation

Operating Principle of Inductive Non-Contact Switch

  1. Uses a high-frequency magnetic field and induced current generated by the oscillation (up to the specified voltage) of the coil in the switch.

  2. An eddy current is generated on the metal surface by the self-inductance effect when metal is present in the high-frequency magnetic field.

  3. The generated eddy current weakens the high-frequency magnetic field by the same amount as the magnetic flux change caused by the switch.

  4. ON-OFF is determined by evaluating whether the high-frequency magnetic field is weakened or not (calculates the voltage difference between the metal and the coil).

Circuit Diagrams

System Diagram

Terminal Function

Pin No. Description
1 IGN1
2 Brake Signal
3 -
4 B+
5 Stop Lamp Signal
6 Ground

Troubleshooting

Troubleshooting

  1. Component Inspection

    Items Cause Symptom
    Fuse Switch Loose fuse connection, blown fuse

    • DTC: P0504

    • Symptom: Shift problems, no start, cruise control cancel function problem, EPB cancel function malfunction, stop lamp malfunction, ESC OFF lamp illuminated.

    		 ① Check the signal waveform using an oscilloscope on each part while the vehicle is accelerating/braking. (Refer to Brake Light Switch Circuit Inspection Procedure)

    ② Refer to the applicable part repair procedure if any abnormality is found in the waveform (refer to the repair procedure for the relevant part and replace if necessary)
    Fuse Relay Loose fuse connection, blown fuse

    • DTC: P0504

    • Symptom: Shift problems, no start, cruise control cancel function problem, EPB cancel function malfunction, stop lamp malfunction, ESC OFF lamp illuminated.
    Stop Lamp Switch

    • Damaged wiring of each component

    • Incorrect connector connection

    • Faulty component

    • DTC: P0504

    • Symptom: Shift problems, no start, cruise control cancel function problem, EPB cancel function malfunction, stop lamp malfunction, ESC OFF lamp illuminated.
    Stop Lamp Electronic
    Module (if applicable)

    • DTC: P0504, C2130, C2131

    • Symptom: Shift problems, no start, cruise control cancel function problem, EPB cancel function malfunction, stop lamp malfunction, ESC OFF lamp illuminated.
    Engine Control Module (ECM)

    • DTC: P0504

    • Symptom: Shift problems, cruise control cancel problem
    Body Control Module (BCM)

    • Gear Shifting Concerns
    Shift Lock Solenoid

    • Gear Shifting Concerns
    Inhibitor Switch

    • Symptom: Shift problems, no-start, cruise control cancel problem, EPB release function problem
    Smart Key Unit (SMK)

    • Starting Failure
    Electronic Parking Brake (EPB)

    • Symptom: EPB cancel function problem, ESC OFF lamp illuminated.
    ABS/ESC Control Module
    (Pressure Sensor)

    • Symptom: ESC OFF lamp illuminated.

  2. Symptom Diagnostics

    Symptom Possible Cause
    Starting Problems Switch fuse, relay fuse, stop lamp switch, electronic stop lamp module, ABS/ESC control module, each wire, connector ① Check the signal waveform using an oscilloscope on each part while the vehicle is accelerating/braking. (Refer to Brake Light Switch Circuit Inspection Procedure)

    ② Refer to the applicable part repair procedure if any abnormality is found in the waveform (refer to the repair procedure for the relevant part and replace if necessary)
    Gear Shifting Concerns Switch fuse, relay fuse, brake light switch, electronic brake light module, BCM, ECM, inhibitor switch, each wire, connector
    ESC OFF lamp illuminated Switch fuse, relay fuse, stop lamp switch, electronic stop lamp module, ABS/ESC control module, each wire, connector
    P0504 Switch fuse, relay fuse, brake light switch, electronic brake light module, ECM, each wire, connector
    Stop lamp does not operate Switch fuse, relay fuse, brake light switch, electronic brake light module, wire/connector disconnected
    Stop lamp always
    on    		 Stop lamp switch, stop lamp electronic module,
    Wiring short circuit, blown fuse

  3. Stop Lamp Switch System Diagnosis

    SSEM: Stop Lamp Electronic Module

  4. Refer to the DTC Chart when the applicable DTCs are displayed.

Repair Procedures

Adjustment

  1. Check the clearance between the stop lamp switch and the bracket.

    Stop lamp switch clearance (A): 1.0-2.0 mm (0.04-0.08 in.)

  2. If the clearance between the stop lamp switch and the bracket is not 1.0 - 2.0 mm (0.04 - 0.08 in.), check the mounting clip and other parts around the stop lamp switch.

  3. If everything is normal, reinstall the stop lamp switch and check the clearance again.

Inspection

1. Check Fuses

Install a test fuse in place of the switch fuse and the relay fuse part to confirm normal operation.

2. Analyze CAN Data

  1. Analyze the KDS data and check the brake switch for proper operation.

    1. Connect the KDS to the self-diagnosis connector.

    2. Turn the ignition switch ON.

    3. Press the brake pedal.

    4. Check the "Brake Switch" category, which displays the KDS "Sensor Data".

      Normal signal pattern: The brake pressure sensor signal value will change according to the brake switch ON/OFF state.

3. Inspect Each Connector

Check each connector for damage, overheated terminals, or incomplete connection.

[Engine Room Junction Box]

[ABS/VDC Control Module]

4. Inspect the Stop Lamp Circuit.

Connect the probe to each terminal wire and check the signal waveform.

[Brake Light Switch Input/Output]

[Oscilloscope Waveform Screen]

Replacement

  1. Turn the ignition switch OFF and disconnect the negative (-) battery terminal.

  2. Remove the airbag lower panel.

    (Refer to Body (Interior and Exterior) - "Lower Panel Emergency Pad")

  3. Disconnect the stop lamp switch connector (A).

  4. Pull the lock plate (A) as shown by the arrow.

  5. Turn the brake switch 45° counterclockwise and remove it.

  6. Inspect the removed stop lamp switch according to the procedures described below.

    1. Confirm proper connection with the terminal part.

      • Confirm that the connector is properly secured and that the connection mark is present.

  7. Hold the brake pedal arm and fully insert the brake switch so that the contact part is not visible.

  8. After insertion, turn the brake switch 45° clockwise, then install the locking plate by pressing.

  9. Check the clearance between the stop lamp switch and the bracket.

    Stop lamp switch clearance (A): 1.0-2.0 mm (0.04-0.08 in.)

  10. Connect the connector of the brake light switch (A).

  11. Install the remaining parts in the reverse order of removal.

Test yourself

A quick Kia Forte BD quiz: every answer comes with an explanation and a link to the manual page.