P0571
DTC P0571 BRAKE SWITCH "A" CIRCUITComponent Location:
GENERAL DESCRIPTION
Brake switch connected to brake pedal transfers brake operating state to ECM. For diagnosis of abnormal operation of Brake switch, two types of signals(one from Brake warning lamp switch, the other from Brake checking switch) are used and those two types output different signals at both condition, depressing or releasing brake pedal. When brake pedal is depressed brake checking switch outputs B+ voltage while brake warning lamp switch emits 0V. Conversely, when brake pedal is released, the output signals of each switch are opposite.
DTC DESCRIPTION
Checking input signals from brake lamp switch every 2 sec. under detecting condition, if the operation state of brake lamp switch does not change for more than 2 sec., PCM sets P0571. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition:
Schematic Diagram:
MONITOR SCANTOOL DATA
1. IG "OFF" & connect Scantool.
2. ENG "ON" and warm -up the engine to normal operating temperature.
3. Monitor "Brake Switch" parameter on the service data with stepping on and off the brake
4. Are those related current data displayed correctly ?
YES: Fault is intermittent caused by poor contact in Sensor's and/or PCM's connector or was repaired and PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure
NO: Go to "Terminal and Connector Inspection" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals. 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?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure
NO: Go to "Power Circuit Inspection "procedure.
POWER CIRCUIT INSPECTION
1. Check voltage
1. IG "OFF".
2. Disconnect the PCM connector.
3. IG "ON" and ENG "OFF"
4. During taking oft the brake: Measure the voltage between terminal 23 of PCM harness connector and chassis ground.
Specification:
5. During stepping on the brake: Measure the voltage between terminal 23 of PCM harness connector and chassis ground.
6. Is the measured voltage within specification ?
YES: Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to "Check open in harness" as follows.
2. Check open in harness
1. IG "OFF".
2. Disconnect the brake switch and PCM connector.
3. Measure the resistance between terminal 23 of PCM harness connector and terminal 1 of Brake switch harness side.
Specification : Approx. below 1 Ohm
4. Is the measured resistance within specification ?
YES: Go to "Check voltage" as follows.
NO: Repair open in circuit and go to "Verification of Vehicle Repair" procedure.
3. Check voltage
1. IG "OFF".
2. Disconnect the brake switch connector.
3. Measure the voltage between brake lamp switch terminal and chassis ground.
4. IG "ON" and ENG "OFF"
Specification:
5. Measure the voltage between brake lamp switch terminal and chassis ground.
6. Is the measured voltage within specification ?
YES: Substitute with a known - good brake switch and check for proper operation. If the problem is corrected, replace brake switch and go to "Verification of Vehicle Repair" procedure..
NO: Check the fuse between battery and brake switch.
Repair open or short in power circuit of brake switch and 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. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions
4. Monitor that all readiness tests have been verified as "Complete"
5. Are any DTCs present?
YES: Go to the applicable trouble shooting procedure.
NO: System is performing to specification at this time.