C1513 Brake Switch Circuit Error

COMPONENT LOCATION

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GENERAL DESCRIPTION
This switch is mounted on the pedal assembly and is used to indicate brake pedal status to the HECU.
The switch is turned on when brake is pressed.
The brake light switch is a normally-open contact which runs to battery voltage when active (brake pressed).
When passive (brake released), the cable is grounded via the brake light bulbs.
DTC DESCRIPTION
The brake light signal is a reference to judge driver’s intention for braking.
The HECU checks open or short circuit of brake light switch for normal ESP control.
If an error is present, the warning lamp will illuminate.
DTC DETECTING CONDITION
 
ItemDetecting ConditionPossible cause
DTC Strategy
Open circuit monitoring
Open circuit in brake switch line
Faulty brake light switch
Faulty input stage in HECU
Enable Conditions
If both BLS(brake lamp switch) and BS(brake switch) have a same state and MCP (Master Cylinder Pressure) >20bar for 500ms.
Outside an ABS/ESP control, and after normal operation of MCP, If the pressure sensor signal is higher than 20bar and BLS is low for 3sec.
If the BLS/BS changed more than 40times and MCP>20bar for 5sec.
While Vehicle speed > 10km/h, TPS>5%, MCP<7bar, if BLS is high over 1min.
Fail Safe
Inhibit the ESP control and allow the ABS/EBD control.
The ESP warning lamp is activated.
SPECIFICATION
 
Brake Light SwitchVoltage Range of “High”Voltage Range of “Low”
7.0V ~ 16.0V0V ~ 3.0V
DIAGNOSTIC CIRCUIT DIAGRAM

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MONITOR SCANTOOL DATA
1.
Connect scantool to Data Link Connector(DLC)
2.
Ignition “ON” & Engine “OFF”.
3.
Press the brake pedal.
4.
Monitor the “BRAKE SWITCH” parameter on the scantool.
 It is changed to ON/OFF.

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Fig 1) Service data at not pressing the break pedal
Fig 2) Service data at pressing the break pedal
5.
Whenever brake pedal is pushed down, is the brake switch’s scantool data changed ON/OFF?
 

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▶ Fault is intermittent caused by poor connection in brake light switch harness and/or HECU’s connector or was repaired and HECU memory was not cleared.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Repair or replace as necessary 

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▶ Go to “Terminal and Connector Inspection” procedure.
TERMINAL AND CONNECTOR INSPECTION
1.
Many malfunctions in the electrical system are caused by poor harness(es) and terminal condition. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3.
Has a problem been found?
 

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▶ Repair as necessary 

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▶ Go to “Signal Circuit Inspection (brake pedal isn’t depressed)” procedure.
SIGNAL CIRCUIT INSPECTION
Signal circuit inspection (brake pedal isn’t pressed)
■ Open or Short Check
1.
Ignition “ON” & Engine “OFF”.
2.
Measure voltage between stop lamp switch (brake switch) terminal of the HECU harness connector and hassis ground.
Specification : Stop lamp switch – 0V
Brake switch B – B+

 

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3.
Is the measured waveform within specifications?
 

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▶ Go to “Signal Circuit Inspection (brake pedal is pressed)” procedure.

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▶ Check for open or blown fuse referring to “Circuit Diagram”.
Repair open or short in power circuit between battery and HECU harness connector 
If there is no problem in circuit, Go to “Component Inspection” procedure.
Signal Circuit Inspection (brake pedal is pressed)
■ Open or Short Check
1.
Ignition “ON” & Engine “OFF”.
2.
Press the brake pedal.
3.
Measure voltage between stop lamp switch (brake switch) terminal of the HECU harness connector and chassis ground.
Specification : Stop lamp switch – B+
Brake switch B – 0 V

 

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4.
Is the measured waveform within specifications?
 

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▶ Go to “Component Inspection” procedure.

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▶ Check for open or blown fuse referring to “Circuit Diagram”.
Repair open or short in signal circuit between battery and HECU harness connector 

 

COMPONENT INSPECTION
■ Brake light switch Check
1.
Ignition “OFF” & Engine “OFF”.
2.
Disconnect the stop lamp switch connector.
3.
Measure resistance between power terminal and siganl terminal of the stop lamp switch connector.
Specification :
Resistance between terminals of the stop lamp switch – ∞Ω (when the plunger is pushed down), 0Ω (when the plunger isn’t pushed down).
Resistance between the terminals of the brake switch – ∞Ω (when the plunger is not pushed down), 0Ω (when the plunger is pushed down).

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4.
Is the measured value within specifications?
 

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▶ Fault is intermittent caused by poor connection in brake light switch harness and/or HECU’s connector.

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▶ Substitute with a known-good brake light switch and check for proper operation.
If problem is corrected, replace brake light switch

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