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Brake Switch: Troubleshooting

WARNING: This page is about a different car, the 2022 Kia Seltos. However, it is still accessible from the selected car via links, so may be relevant.
  1. Part diagnosis
    Items Cause Symptom  
    Switch fuse Faulty fuse connection, Damaged fuse
    • DTC Code: P0504
    • Symptom: Shifting gear trouble, Starting failure, Cruise control function cancellation trouble, EPB function cancellation trouble, Stop lamp lighting trouble, ESC OFF light illuminated.
    1. A waveform inspection is performed using an oscilloscope on each part during vehicle acceleration/braking. (Refer to "INSPECTION ").
    2. Refer to the relevant repair procedures of the part when something abnormal is discovered in the waveform (Refer to the repair procedures of the relevant part and if necessary replace it)
    Relay fuse Faulty fuse connection, Damaged fuse
    • DTC Code: P0504
    • Symptom: Shifting gear trouble, Starting failure, Cruise control function cancellation trouble, EPB function cancellation trouble, Stop lamp lighting trouble, ESC OFF light illuminated.
    Stop lamp switch
    • Damaged wiring of each part
    • Faulty connection to connector
    • Each part is defective
    • DTC Code: P0504
    • Symptom: Shifting gear trouble, Starting failure, Cruise control function cancellation trouble, EPB function cancellation trouble, Stop lamp lighting trouble, ESC OFF light illuminated.
    Stop signal electronic module (If it applies)
    • DTC Code: P0504, C2130, C2131
    • Symptom: Shifting gear trouble, Starting failure, Cruise control function cancellation trouble, EPB function cancellation trouble, Stop lamp lighting trouble, ESC OFF light illuminated.
    Engine control module (ECM)
    • DTC Code: P0504
    • Symptom: Shifting gear trouble, Cruise control function cancellation trouble
    Body control module (BCM)
    • Shifting gear trouble
    Shift-lock solenoid
    • Shifting gear trouble
    Inhibitor switch
    • Symptom: Shifting gear trouble, Starting failure, Cruise control function cancellation trouble, EPB function cancellation trouble
    Smart Key Unit (SMK)
    • Starting failure
    Electronic parking brake
    • Symptom: EPB function cancellation trouble, ESC OFF light illuminated.
    ABS/ESC control module (Pressure sensor)
    • Symptom: ESC OFF light illuminated.
  2. Symptom diagnosis
    Symptom Part that could be the cause  
    Trouble starting Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, ABS/ESC control module, Each wire, Connector
    1. Inspect waveform using an oscilloscope on each part during vehicle acceleration/braking. (Refer to "TROUBLESHOOTING ")
    2. Refer to the relevant repair procedures of the part when something abnormal is discovered in the waveform (Refer to the repair procedures of the relevant part and if necessary replace it)
    Trouble shifting gears Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, BCM, ECM, Inhibitor switch, Each wire, Connector
    ESC OFF light illuminated Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, ABS/ESC control module, Each wire, Connector
    P0504 Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, ECM, Each wire, Connector
    Stop lamp not working Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, Wire/Connector disconnected
    Stop lamp always turned on Stop lamp switch, Stop signal electronic module, Wiring short circuit, Damaged fuse
  3. Stop lamp switch system diagnosis
    G13481674Courtesy of KIA MOTORS AMERICA, INC.

    •: Always ON ◦: ON - OFF operation X: Always OFF

    Symptom (When the ESC OFF lamp illuminated) System Remedy
    (1)
    Power Supply (B+)    		 (2)
    End of the Stop Lamp Switch    		 (3)
    SSEM Input    		 (4)
    SSEM Output
    Switch internal open • x x x Replace with a new one and check it.
    Switch internal short • • • • Check the stop lamp switch after removing It 
    1. Switch failure: Replace with a new one. 
    2. Wiring failure: Check the suspected part.
    SSFM internal short • ◦ ◦ • or X Check the SSEM after removing it 
    1. SSEM failure: Replace with a new one.
    2. Wiring failure: Check the suspected part.
    SSEM Internal open • ◦ ◦ X Check the SSEM alter removing it 
    Power supply open X X X X Check the power supply connector or the fuse
    Power supply short (Current reduction) • ◦ ◦ • or X If the power supply line is shorted, SSEM ON-OFF may not be operating well due to the amount of current reduction Check for fuse damage.
    Failure between SSEM and output • ◦ X X Check the connector and the wiring
    Failure between SSEM and Stop lamp (Not operating the stop lamp No signals on KDS) • ◦ ◦ ◦ Check the connector and the wiring

    SSEM: Stop Signal Electronic Module

  4. (Refer to "ABS/ESC SYSTEM DTCS ").
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