Kia Forte: Brake System / Stop Lamp Switch

Kia Forte 2019-2024 (BD) Service Manual / Brake System / Brake System / Stop Lamp Switch

Components and components location

Components

1. Brake pedal member assembly
2. Stop lamp switch

3. Brake pedal arm

Description and operation

Operation

Operation principle of inductive non-contact switch

1.	Use the high frequency magnetic field and the induced current that are generated by oscillation (to approved voltage) of coil in switch.

2.	The eddy current is generated on surface of metal by self inductance effect if there is metal in high frequency magnetic field.

3.	The eddy current that is generated attenuates the high frequency magnetic field as much as amount of generated by disturbing the switch's magnetic flux.

4.	ON-OFF by judging whether high voltage magnetic field is attenuates or not(calculate the voltage difference by length between metal and coil)

Schematic diagrams

System circuit diagram

Terminal function

Pin No	Description
1	IGN1
2	Brake signal
3	-
4	B+
5	Stop lamp signal
6	Ground

Troubleshooting

Part diagnosis

Items

Cause

Symptom

Switch fuse

Faulty fuse connection, Damaged fuse

–	DTC Code : P0504

–	Symptom : Shifting gear trouble, Starting failure, Cruise control function cancelation trouble, EPB function cancelation 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 stop lamp switch circuit inspection procedures)

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 cancelation trouble, EPB function cancelation 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 cancelation trouble, EPB function cancelation 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 cancelation trouble, EPB function cancelation trouble, Stop lamp lighting trouble , ESC OFF light illuminated.

Engine control module(ECM)

–	DTC Code : P0504

–	Symptom :Shifting gear trouble,Cruise control function cancelation 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 cancelation trouble, EPB function cancelation trouble

Smart Key Unit(SMK)

–	Starting failure

Electronic parking brake

–	Symptom : EPB function cancelation trouble , ESC OFF light illuminated.

ABS/ESC control module
(Pressure sensor)

–	Symptom : ESC OFF light illuminated.

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 stop lamp switch circuit inspection Procedures) 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 SSEM : Stop Signal Electronic Module

4.	Refer to DTC guide when the related DTC codes are displayed.

Repair procedures

Adjustment

Confirm the gap between stop lamp switch and bracket.

Stop lamp clearance (A) :

1.0 - 2.0 mm (0.04 - 0.08 in.)

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

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

Inspection

1. Fuse inspection

Mount the test fuse to the switch fuse and relay fuse part to confirm a normal joint fit.

2. KDS Data Analysis

Analyze KDS data and check for any abnormality with the stop lamp switch.

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

(2)	Turn the spark switch on.

(3)	Step on the brake pedal.

(4)

Inspect the "brake switch" category that displays the "sensor data" KDS.

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

3. Inspection of connector by each part

Check for damage, terminal surge or incomplete connection in each connector.

[Engine room junction box]

[ABS/VDC control module]

4. Inspect the stop lamp circuit

Connect probe to each terminal wire and confirm oscilloscope waveform.

[Stop lamp switch input/output]

[Oscilloscope waveform screen]

Replacement

1.	Switch "OFF" ignition and disconnect the negative (-) battery terminal.

2.	Remove the crash pad lower panel. (Refer to Body (Interior and Exterior) - "Crash Pad Lower Panel")

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

4.	Pull the locking plate (A) as indicated by the arrow.

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

Inspect a removed stop lamp switch along the below procedures.

(1)

Confirm a normal connection with terminal part.

–	A confirmation can be made to see if the connector has been secured properly and if a connection mark is present.

7.	Fix the brake pedal arm and insert fully the brake switch so that the contact part is invisible.

8.	After inserting, turn the brake switch 45° clockwise, and then assemble locking plate by pushing.

Confirm the gap between stop lamp switch and bracket.

Stop lamp clearance (A) :

1.0 - 2.0 mm (0.04 - 0.08 in.)

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

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

10.	Connect the stop lamp switch connector (A).

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

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