Hyundai Elantra: Brake System / Stop Lamp Switch

Hyundai Elantra (CN7) 2021-2024 Service Manual / Brake System / Brake System / Stop Lamp Switch

Components and components location

Components

1. Brake member assembly
2. Stop lamp switch

3. Brake pedal arm assembly
4. Brake pedal pad

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, ESP 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 , ESP 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 , ESP 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 , ESP 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 , ESP OFF light illuminated.

ABS/VDC control module
(Pressure sensor)

–	Symptom : ESP 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/VDC 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
ESP OFF light illuminated	Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, ABS/VDC control module, Each wire, Connector
P0504	Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, ECM, Each wire, Connector
Stop lamp does notworking	Switch fuse, Relay fuse, Stop lamp switch, Stop signal electronic module, Wire/Connector disconnected
Stop lamp always turns 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.

Schematic diagrams

Schematic Diagram

System Circuit Diagram

Terminal Function

Teminal	Description
1	IGN1
2	Engine Control Module (ECM)
3	-
4	B+
5	Stop Lamp
6	Gruound

Repair procedures

Adjustment

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

2.	Remove the lower crash pad. (Refer to Body - "Crash Pad")

Confirm the gap between stop lamp switch and bracket.

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

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

5.	If there is normal, remove the stop lamp switch and then install again.

Inspection

1. Fuse Inspection

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

2. GDS Data Analysis

Analyze GDS data and confirm if there is anything wrong with the stop lamp switch.

(1)	Connect the GDS 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" GDS.

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

3. Inspection of Connector by Each Part

Check to see whether or not each connector has been damaged, or terminal surge, or incomplete connection has taken place

[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]

Removal

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

2.	Remove the lower crash pad. (Refer to Body - "Crash Pad")

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

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

5.	Turn stop lamp switch 45° counterclockwise and remove it.

Inspect a removed stop lamp switch along the below procedures.

(1)

Confirm a normal connection with terminal part

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

Installation

1.	Insert fully the stop lamp switch as hiding contact part.

2.	After inserting, turn the stop switch 45° clockwise, and then assemble locking plate (A) by pushing.

Confirm the gap between stop lamp switch.

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 1.0-2.0mm (0.04-0.08in), perform the above process again.

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

5.	Install the lower crash pad. (Refer to Body - "Crash Pad")

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