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Eric
Eric, Automotive Repair Shop Manager
Category: Kia
Satisfied Customers: 30301
Experience:  20+ yrs. experience as repair shop manager and technician.
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Kia sorento: XXXXX XXXXX engine light..Brake switch..find anything

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my 07 kia sorento has the check engine light on and the esc off light on. It is reading code P0504 Brake switch a/b correlation. I can't find anything explaining what that means....can anyone tell me?
Hi,

normally, this is a faulty brake switch, which is located at top of brake pedal. Below is definition and testing:

DTC Detecting Condition
Item
Detecting condition
Possible cause
DTC Strategy
? Comparing 2 brake signals during driving
? Poor connection
? Open or short in brake switch
? Faulty Brake switch
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 dring 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


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. Votage check
(1) IG Key "OFF".
(2) Disconnect the ECM connector.
(3) IG Key "ON" and keep the brake taking off.
(4) Measure the voltage between terminal 21 of ECM harness connector and chassis ground.
(5) Measure the voltage between terminal 23 of ECM harness connector and chassis ground .
(6) Keep the brake stepping on.
(7) Measure the voltage between terminal 21 of ECM harness connector and chassis ground.
(8) Measure the voltage between terminal 23 of ECM 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

graphic

(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 ECM connector.
(3) Measure the resistance between terminal 21 of ECM harness connector and terminal 4 of Brake switch harness side.
(4) Measure the resistance between terminal 23 of ECM harness connector and terminal 3 of Brake switch harness side.
A. Specification : Approx. below 1?

graphic

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

graphic


(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.
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