4.
Monitor the "STOP LAMP SWITCH" parameter on the scantool.
Specification : Lateral G sensor : ± 0 G, YAW rate Sensor : ± 0 deg/s
The brake light switch indicates brake pedal status to the ABS control unit. The brake light switch which is dual switch type send brake light signal to HECU. The switch is turned on when brake is depressed. The brake light switch runs to battery voltage when brake depressed. but The brake light switch doesn't run to battery voltage when brake is not depressed. On the contrary, The brake switch is normally close type which doesn't run to battery voltage when brake depressed.
The brake light signal is a reference to judge driver's intention for braking and The HECU checks open or short circuit of brake light switch for normal ABS/ESP control. If the brake light switch have an error, warning ramp will be turned ON.
Item | Detecting Condition | Possible cause | |
DTC Strategy | ● Voltage monitoring | ● Open circuit in brake switch line ● Faulty brake light switch ● Faulty HECU | |
Case 1 | Monitoring Period | ● Continuous (only no under voltage is not detected) | |
Enable Conditions | ● If the BLS-signals is high for 60 s, while the gas pedal is stepped, with vehicle speed ＞ 10.8 km/h, offset compensated pressure ＜ 5 bar and no control is active, a fault is set. | ||
Case 2 | Monitoring Period | ● Continuous (only normal voltage) | |
Enable Conditions | ● For redundancy reasons an additional BLSpVor-signal is created by the pressure sensor signal. If the pressure sensor is compensated, the threshold for generating the BLSpVor signal is 10 bar. If the pressure sensor is not compensated, the threshold is increased by 15 bar. If this signal is set without any hardware-BLS-signals being set for at least 1 s. ● If the pressure signal is higher than 80bar and not both of the hardware-BLS are set, a fault is stored after 1 s. | ||
Fail Safe | ● Inhibit the ESP control and allow the ABS/EBD control. ● The ESP warning lamps are activated. | ||
Connect scantool to Data Link Connector(DLC).
Ignition "ON" ＆ Engine "ON"
Press the brake pedal.
Monitor the "STOP LAMP SWITCH" parameter on the scantool.
Specification : Lateral G sensor : ± 0 G, YAW rate Sensor : ± 0 deg/s
Whenever brake pedal is pushed down, is the brake switch’s scantool data changed ON/OFF?
▶ Fault is intermittent caused by poor connection in Yaw Rate & Lateral G sensor 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.
▶ Go to "W/Harness Inspection" procedure.
Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and then go to "Verification of Vehicle Repair" procedure.
▶ Go to "Power Circuit Inspection" procedure.
Ignition "ON" ＆ Engine "OFF".
Press the brake pedal.
Measure voltage between the terminal "30" of the HECU harness connector and chassis ground.
Specification : Brake Switch - Approx. B+
Is the measured voltage within specifications?
▶ Fault is intermittent caused by open or short harness in brake light switch, faulty brake lamp switch or was repaired and HECU memory was not cleared. Go to the applicable troubleshooting procedure.
▶ Check for open or blown 15 A STOP fuse referring to "Circuit Diagram" . Check for damaged harness and poor connection in the power harness between the battery terminal(+) and the terminal "30" of the HECU harness connector . Repair as necessary and then go to "Verification of vehicle Repair" procedure. If OK, Go to "Component Inspection" Precedure.
Connect a ohmmeter to the connector of brake light switch, and check whether or not there is continuity when the plunger of the brake light switch is pushed in and when it is released. The switch is in good condition if there is no continuity when the plunger is pushed
Is there no continuity when the plunger is pushed?
▶ Fault is intermittent caused by open harness in brake light switch line, faulty brake lamp switch or was repaired and HECU memory was not cleared. Go to the applicable troubleshooting procedure.
▶ Substitute with a known-good brake lamp switch and check for proper operation. If problem is corrected, replace brake light switch and then go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes(DTCs)" mode
Using a scantool, Clear DTC.
Operate the vehicle within DTC Detecting Condition in General Information.
Are any DTCs present ?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
