P0504 Lexus Code - Brake Switch Circuit 'A' / 'B' Correlation
Quick Answer
The Stop Lamp Switch is a duplex system that transmits two signals: STP and ST1-. Common causes include Faulty Stop Lamp Switch (Brake Switch), Blown Stop Lamp Bulb, Stop Lamp Switch harness open or shorted. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0504 Lexus indicates Brake Switch Circuit 'A' / 'B' Correlation.
- Common causes
- Common causes include Faulty Stop Lamp Switch (Brake Switch), Blown Stop Lamp Bulb, Stop Lamp Switch harness open or shorted.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0504 Lexus Description
What are the Possible Causes of the DTC P0504 Lexus?
- Faulty Stop Lamp Switch (Brake Switch)
- Blown Stop Lamp Bulb
- Stop Lamp Switch harness open or shorted
- Stop Lamp Switch circuit poor electrical connection
- Faulty Engine Control Module (ECM)
How to Fix the DTC P0504 Lexus?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0504 Lexus code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P0504 Lexus code?
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Need Help with the Code?
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Frequently Asked Questions about P0504 Lexus Code
No Frequently Asked Questions about P0504 Lexus Code found.
Discuss the causes and fixes for P0504 Lexus OBDII Code
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What model and year is your Lexus? perhaps the stop lamp switch is obstructing the brake pedal.
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2003 Lexus LS430. I'm getting code P0504 with OBDII but with no SES or CE lights on dash. Brake light bulbs all seem to work normally with brake pedal press.
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i have the same code in my 2006 lexus is350, all brake lights work, replaced the brake pedal switch 3 times (2 times with an autozone one, and lastly an OEM one from japan that cost me $95 from the dealership) what the hell else could it be?
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How long it takes for brake switch to fail? within months, days, hours? if is within days or months, then the bracket where the switch is mounted may be bent or damage. If is within hours, then the problem is more than likely the wire from the sensor to the control unit.
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i can have the dealer clear the code, and within 30-45 minutes of highway driving, it will come back on. could it be a fuse? or do i just need to run new wire from the switch to the ECU?
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Check if you have battery voltage at terminals 2 and 3. There should be battery voltage with the ignition ON. If you have battery voltage and you know for your the switch is OK, then you can run a wire from the switch to ECM. Also, if you are planning to test wires with a test light, I recommend disconnecting the ECM first, you can easily damage the ECM with a test light.
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