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 depressed.
The brake light switch
is a normally-open contact which runs to battery voltage when active
(brake depressed).
When passive (brake not
depressed), the cable is grounded via the brake light bulbs.
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 ESC control.
If an error is present,
the warning lamp will illuminate.
Item
|
Detecting
Condition
|
Possible 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/ESC 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 ESC control and allow the
ABS/EBD control. |
| •
|
The ESC warning lamp is
activated. | |
Brake Light Switch
|
Voltage
Range of "High"
|
Voltage
Range of "Low"
|
7.0V ~
16.0V
|
0V ~
3.0V
|
| 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.
Specification
: It is changed to
ON/OFF.
|
|
| 5. |
Whenever brake pedal is pushed down, is the
brake switch's scantool data changed ON/OFF?
|
|
▶ 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 and then go to "Verification Of Vehicle Repair"
procedure.
|
|
|
▶ 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?
|
|
▶ Repair as
necessary and then go to "Verification Of Vehicle Repair"
procedure.
|
|
|
▶ Go to
"Signal Circuit Inspection (brake pedal isn't depressed)"
procedure.
|
|
| Signal circuit inspection (brake pedal
isn't depressed) |
Open or Short Check
| 1. |
Ignition "ON" & Engine
"OFF". |
| 2. |
Measure voltage between brake light switch
signal A, B terminal of the HECU harness connector and chassis
ground.
Specification
: Brake light switch A -
0V
Brake light switch B -
B+
| |
| 3. |
Is the measured waveform within
specifications?
|
|
▶ Go to
"Signal Circuit Inspection (brake pedal is depressed)"
procedure.
|
|
|
▶ Check for
open or blown 15A, 10A fuse referring to "Circuit
Diagram".
▶ Repair open or short in
power circuit between battery and HECU harness connector and
then, go to "Verification Of Vehicle Repair"
procedure.
▶ If there is no problem
in circuit, Go to "Component Inspection"
procedure.
|
|
Signal Circuit Inspection (Brake Pedal Is
Depressed)
Open or Short Check
| 1. |
Ignition "ON" & Engine
"OFF". |
| 2. |
Press the brake
pedal. |
| 3. |
Measure voltage between brake light switch
signal A, B terminal of the HECU harness connector and chassis
ground.
Specification
: Brake light switch A -
B+
Brake light switch B -
0V
| |
| 4. |
Is the measured waveform within
specifications?
|
|
▶ Fault is
intermittent caused by poor connection in brake light switch
harness and/or HECU's connector.
Go
to "Verification Of Vehicle Repair"
procedure.
|
|
|
▶ Check for
open or blown 15A, 10A fuse referring to "Circuit
Diagram".
▶ Repair open or short in
power circuit between battery and HECU harness connector and
then go to "Verification Of Vehicle Repair"
procedure.
▶ If there is no problem
in circuit, Go to "Component Inspection"
procedure.
|
|
Brake light switch Check
| 1. |
Ignition "ON" & Engine
"OFF". |
| 2. |
Disconnect the brake light switch
connector. |
| 3. |
Measure resistance between power terminal and
siganl terminal of the brake light switch A, B
connector.
Specification
: Resistance between terminals of the
brake light switch A - ∞Ω (when the plunger is pushed down),
0Ω (when the plunger isn't pushed down).
Resistance between the terminals of the
brake light switch B - ∞Ω (when the plunger is not pushed
down), 0Ω (when the plunger is pushed
down).
| |
| 4. |
Is the measured value within
specifications?
|
|
▶ Fault is
intermittent caused by poor connection in brake light switch
harness and/or HECU's connector.
Go
to "Verification Of Vehicle Repair"
procedure.
|
|
|
▶
Substitute with a known-good brake light switch and check for
proper operation
If problem is
corrected, replace brake light switch and then go to
"Verification Of Vehicle Repair"
procedure.
|
|
| Verification of Vehicle
Repair |
After a repair, it is
essential to verify that the fault has been corrected.
| 1. |
Connect scantool and select "Diagnostic
Trouble Codes(DTCs)" mode. |
| 2. |
Using a scantool, Clear
DTC. |
| 3. |
Operate the vehicle within DTC Detecting
Condition in General Information. |
| 4. |
Using a scantool, Check DTC
present. |
| 5. |
Are any DTCs present ?
|
|
▶ Go to the
applicable troubleshooting procedure.
|
|
|
▶ System
performing to specification at this
time.
|
|
