Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer has detected a problem with the brake pressure sensors. These sensors help the car know how hard you're pressing the brake pedal. If they don't agree with each other, the car gets confused.
The vehicle's electronic control module (ECM) monitors the brake pressure sensors to ensure they are providing consistent and accurate readings. If the readings from Sensor A and Sensor B do not match or correlate, the ECM triggers the C0634 code.
Brake pressure sensors A and B are used to measure the pressure applied to the brake system. These sensors send signals to the ECM, which compares the readings to ensure they match. If there is a discrepancy between the two sensors' readings, it indicates a potential fault in one or both sensors, wiring issues, or a problem with the ECM itself.
• ABS warning light on
• Inconsistent brake pedal feel
• Reduced braking performance
• Unusual noises when braking
• Faulty brake pressure sensor A
• Faulty brake pressure sensor B
• Wiring issues or poor connections
• Faulty ECM
ECM: Engine Control Module
ABS: Anti-lock Braking System
• Check for any additional codes and address them first.
• Inspect the wiring and connectors for the brake pressure sensors.
• Test the brake pressure sensors for proper operation.
• Check the ECM for faults.
• Replace faulty brake pressure sensor(s).
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Brake pressure sensor tester
$150 - $500
Moderate
• Chevrolet Silverado
• GMC Sierra
• Cadillac Escalade
• Regularly inspect brake system components.
• Ensure all electrical connections are secure.
• Perform routine vehicle maintenance.
Sensor Issue
• Do not ignore the ABS warning light.
• Have the brake system inspected by a professional.
• Avoid hard braking until the issue is resolved.
Check with the vehicle manufacturer for specific warranty coverage on brake system components.
This code has been reported in vehicles with electronic brake systems, particularly in models with advanced ABS technology.
High – Brake system issues can affect vehicle safety and should be addressed promptly.
Driving with a malfunctioning brake system can be dangerous and may violate vehicle safety regulations.
• Vehicle stationary with engine running.
• Apply and release brake pedal multiple times.
Brake pressure sensors are typically located near the brake master cylinder or integrated within the ABS module.
Q: Can I drive with a C0634 code?
A: It's not recommended to drive with a brake system issue, as it can affect your ability to stop safely.
Q: Will resetting the code fix the problem?
A: Resetting the code may turn off the warning light temporarily, but it won't fix the underlying issue.
Pro · Four-system diagnostics
A handheld scanner aimed at engine, transmission, ABS, and airbag diagnostic work.
Chassis and ABS faults usually need a scanner that can read brake-system data directly.
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Universal · Torque wrench
Useful when reassembly torque matters for wheel, suspension, and under-hood fasteners.
Useful when wheel, hub, or suspension hardware needs correct reassembly torque.
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Universal · Drive-on ramps
Helpful for safer access underneath the vehicle during exhaust, EVAP, and underbody inspection work.
Helpful for safer access during underbody inspection work.
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