Component Location
General Description
Brake switch is connected to brake pedal and transmits brake operating state to ECM.
When the output signal of APS is higher than what driver intended during driving (e.g. short to high voltage line in APS circuit, false signal ), driver depresses brake pedal.
Like this, if driver's decelerating intension is transmitted to ECM (break pedal depressed)when APS output voltage is high, ECM recognizes APS trouble and Limp Home mode is activated.
At Limp Home mode, engine speed is fixed at 1200RPM and engine power generation is limitted.
Even at Limp home mode, if correct APS signal is detected, Limp Home mode is deactivated.
Brake switch, which monitors proper operation of APS, is devided 1 and 2 for the fidelity of brake switch.
DTC Description
When brake switch operates correctly, switch 1 is OFF and switch 2 is ON when releasing brake pedal, while switch 1 is ON and switch 2 is OFF when depressing brake pedal. thus when the signal from a switch is different from the other's, brake switch is in good condition. When the signal from a switch is same as the other's, brake switch is fault.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
DTC Strategy | Signal monitoring
| Brake switch component
Abnormal brake pedal height
Brake switch circuit
|
Enable Conditions | IG KEY "ON"
|
Threshold Value | Wiring open
|
Diagnostic Time | 109 sec.
|
Fail Safe | Fuel cut | NO | |
EGR Off | NO |
Fuel Limit | NO |
MIL | NO |
Specification
Condition | Brake Pedal Released | Brake Pedal Depressed |
switch activated | Switch 1 | Switch 2 | Switch1 | Switch 2 |
OFF | ON | ON | OFF |
Diagnostic Circuit Diagram
Signal Waveform
Fig.1) The waveform of brake signal 1 and 2 are measured simultaneously. Both waveforms are symmetrical.