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Eric
Eric, Automotive Repair Shop Manager
Category: Car
Satisfied Customers: 24948
Experience:  Automotive Repair Shop Manager, Technician/JA Mentor
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What are P0504 and P0571 error codes on Hyundai 07 Sonata

Customer Question

No Comment Added
Submitted: 5 years ago.
Category: Car
Expert:  Eric replied 5 years ago.

Hi,

 

DTC P0504 - brake switch a/b correlation

 

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 cosecutive 2 driving cycle.

DTC Detecting Condition
Item
Detecting Condition
Possible cause
DTC Strategy
? Comparing 2 brake signals during driving
? Poor connection
? Open or Short
? Faulty PCM
Enable Conditions
Case 1
? Engine works
? Vehicle Speed Sensor is abnormal.
Case 2
? Engine works
? Vehicle Speed Sensor is normal and Vehicle Speed is over 20kph during 1sec or more.
Threshold value
? The one brake signal's change duration when another signal has been changed > 0.5 sec
Diagnosis Time
? Continuous
MIL On Condition
? 2 driving cycles

Specification
Item
During taking off the brake
During stepping on the brake
Brake Lamp Switch
0V
Battery voltage
Brake Switch
Battery voltage
0V

 

 

Component Location

 

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 Supply Circuit Inspection
1.Check Voltage
(1)IG Key "OFF".
(2)Disconnect the PCM connector.
(3)IG Key "ON" and keep the brake taking off.
(4)Measure the voltage between terminal 21 of PCM connector and chassis ground.
(5)Measure the voltage between terminal 23 of PCM connector and chassis ground .
(6)Keep the brake stepping on.
(7)Measure the voltage between terminal 21 of PCM connector and chassis ground.
(8)Measure the voltage between terminal 23 of PCM connector and chassis ground .
A.Specification :
Item
During taking off the brake
During stepping on the brake
Brake Lamp Switch
0V
Battery voltage
Brake Switch
Battery voltage
0V

(9)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 Key "OFF".
(2)Disconnect the brake switch and PCM connector.
(3)Measure the resistance between terminal 21 of PCM harness connector and terminal 3 of Brake switch harness side.
(4)Measure the resistance between terminal 23 of PCM harness connector and terminal 1 of Brake switch harness side. Specification : Approx. below 1?

(5)Is the measured resistance within specification ? YES ? Go to "Check voltagen" procedure. NO ? Repair open in circuit and go to "Verification of Vehicle Repair" procedure.
3.Check voltage
(1)IG Key "OFF".
(2)Disconnect the brake switch connector.
(3)Measure the voltage between brake lamp switch terminal and chassis ground.
(4)Measure the voltage between brake switch terminal and chassis ground.
(5)Key "ON".
(6)Measure the voltage between brake lamp switch terminal and chassis ground.
(7)Measure the voltage between brake switch terminal and chassis ground.
A.Specification :
Item
During taking off the brake
During stepping on the brake
Brake Lamp Switch
0V
Battery voltage
Brake Switch
Battery voltage
0V

(8)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.

 

 

DTC P0571 - brake switch A circuit

 

Checking input signals from brake lamp switch. under detecting condition, if the operation state of brake lamp switch does not change for more than 3 sec., PCM sets P0571. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till cosecutive 2 driving cycle.

DTC Detecting Condition
Item
Detecting Condition
Possible cause
DTC Strategy
? PCM detects brake lamp input signal when vehicle stops.
? Poor connection
? Open or short to ground in signal circuit
? Faulty PCM
Enable Conditions
? Engine works
? Vehicle speed signal is normal.
? Vehicle speed >20 kph (during 1sec or more)
Threshold value
? Vehicle speed < 3kph
? Vehicle acceleration< -6kph/s
? Brake lamp "OFF" and not changing of brake lamp signal for more 3 sec.
Diagnosis Time
? Continuous (More than 2 seconds failure for every 2 seconds test )
MIL On Condition
? 2 driving cycles

 

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 Supply Circuit Inspection
1.Check voltage
(1)IG "OFF".
(2)Disconnect the PCM connector.
(3)IG "ON" and ENG "OFF"
(4)During taking off the brake : Measure the voltage between terminal 23 of PCM harness connector and chassis ground.
(5)During stepping on the brake : Measure the voltage between terminal 23 of PCM harness connector and chassis ground.
A.Specification :
Item
During taking off the brake
During stepping on the brake
Brake Lamp Switch
0V
Battery voltage
Brake Switch
Battery voltage
0V

(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?

(4)Is the measured resistance within specification ? YES ? o 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"
(5)Measure the voltage between brake lamp switch terminal and chassis ground.
A.Specification :
Item
During taking off the brake
During stepping on the brake
Brake Lamp Switch
0V
Battery voltage
Brake Switch
Battery voltage
0V

(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.

 

 

The majority of the time it is a faulty brake switch that sets both codes, but I included testing procedures so that you can verify a faulty switch and not a wiring issue

Customer: replied 5 years ago.
Eric , thank you should I just replace the switch and is it just a plug in type
Expert:  Eric replied 5 years ago.

Hi,

 

 

There are 2 locknuts to remove to remove the brake switch, and disconnect the connector. Install new one in reverse. No special programming or anything:

 

graphic

Eric, Automotive Repair Shop Manager
Category: Car
Satisfied Customers: 24948
Experience: Automotive Repair Shop Manager, Technician/JA Mentor
Eric and 3 other Car Specialists are ready to help you
Customer: replied 5 years ago.
Sweet thank you so much Eric, wish I could pay you more , been laid off a month thanks
Expert:  Eric replied 5 years ago.
Thanks for the bonus and it is more than plenty - I enjoy being able to help people save some money and do it themselves. Have a great week!

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