P0504
DTC P0504
GENERAL DESCRIPTION
Brake switch connected to brake pedal transfers brake operating state to PCM. 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 0 V. Conversely, when brake pedal is released, the output signals of each switch are opposite.
DTC DESCRIPTION
Checking output signals from both brake switch when all of them are On or OFF simultaneously, if abnormal signal is detected for more than 0.5 sec., an error is recognized. And if this condition lasts for certain period, PCM sets P0504. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.
DTC Detecting Condition:
DTC DETECTING CONDITION
Specification:
SPECIFICATION
Schematic Diagram:
SCHEMATIC DIAGRAM
MONITOR SCANTOOL DATA
1. Ignition "OFF"
2. Connect Scantool and Engine "ON"
3. Monitor "Brake Switch" parameter on Current Data
4. Are those "Brake Switch" parameters 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. Voltage check
a. Key "OFF".
b. Disconnect the PCM connector.
c. Key "ON" and keep the brake taking off.
d. Measure the voltage between terminal 21 of PCM connector and chassis ground.
e. Measure the voltage between terminal 23 of PCM connector and chassis ground.
f. Keep the brake stepping on.
g. Measure the voltage between terminal 21 of PCM connector and chassis ground.
Specification:
h. Measure the voltage between terminal 23 of PCM connector and chassis ground.
i. 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
a. Key "OFF".
b. Disconnect the brake switch and PCM connector.
c. Measure the resistance between terminal 21 of PCM harness connector and terminal 3 of Brake switch harness side.
d. Measure the resistance between terminal 23 of PCM harness connector and terminal 1 of Brake switch harness side.
Specification : Approx. below 1 ohm
e. Is the measured resistance within specification?
YES - Go to "Check voltage" procedure.
NO - Repair open in circuit and go to "Verification of Vehicle Repair" procedure.
3. Check voltage
a. Key "OFF".
b. Disconnect the brake switch connector.
c. Measure the voltage between brake lamp switch terminal and chassis ground.
d. Measure the voltage between brake switch terminal and chassis ground.
e. Key "ON".
f. Measure the voltage between brake lamp switch terminal and chassis ground.
Specification:
g. Measure the voltage between brake switch terminal and chassis ground.
h. 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 test have been verified as "Complete".
5. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.