P0573 Code: Brake Switch A Circuit High
The PCM thinks the brake pedal is always pressed – brake lights stay on, often from a missing pedal stopper.
Safety first · Consult a professional
- Braking system affected: ABS may be disabled. Drive carefully and have it checked promptly.
At a glance
Severity: Moderate
- Meaning
- Brake Switch A Circuit High
- System
- Speed & Idle Control · Powertrain
- Safe to drive?
- With caution
- Typical repair cost
- $0–$300
- DIY difficulty
- Very easy
P0573 sets when the brake switch A input stays high, so the PCM believes the brake pedal is pressed even while you're accelerating. On many cars the switch plunger rests against a small rubber or plastic stopper on the pedal arm; when that pad crumbles and falls out, the plunger extends as if the pedal were pressed and the brake lights stay on permanently. A switch stuck closed, a pedal that doesn't fully return, or a signal wire shorted to 12 volts give the same result. Besides confusing drivers behind you and draining the battery overnight, a constant brake signal can make the PCM cut throttle under its brake-override logic, so the car may feel sluggish.
Can I keep driving? Short trips are possible, but brake lights that are always on hide your actual braking from following drivers. Fix it promptly, and disconnect nothing that would leave you with no brake lights at all.
Try this first – 5-minute fix
- Confirm the lights stay on With the engine off and the pedal untouched, look at the reflection of your rear end in a window or garage door. Brake lights glowing with nobody on the pedal confirm the fault is at the pedal or switch.
- Look for the missing stopper pad Shine a light under the dash where the switch plunger meets the pedal arm. If there is an empty hole or loose bits of rubber or plastic on the floor, the pad is gone; a replacement costs a few dollars and presses in by hand.
- Lift the pedal by hand Pull the brake pedal up gently with your fingers. If the lights go out, the pedal isn't returning fully: remove any floor mat or object in the way and check the return spring, then readjust the switch if needed.
- Clear the code and test cruise control After the fix, clear the code, check that the lights switch on and off with the pedal, and make sure cruise control engages on a test drive.
How to read P0573
- P Powertrain
- 0 Generic (SAE)
- 5 Speed, idle & inputs
- 73 Specific fault
Symptoms
- Brake lights stay on with the pedal released and the key off
- Battery dead after the car sits overnight
- Cruise control won't engage
- Sluggish acceleration or throttle cut when brake override thinks both pedals are pressed
- Transmission not locking the torque converter, slightly worse fuel economy
- Start-stop or push-button start behaving oddly
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Stopper pad on the pedal arm crumbled or fallen out
- Brake switch stuck closed internally
- Switch misadjusted or pedal not returning fully (weak return spring, floor mat, sticky pivot)
- Signal wire shorted to a 12-volt circuit
- Aftermarket LED bulbs or trailer module back-feeding the brake lamp circuit
- Worn pedal pivot bushing letting the pedal sag
- PCM or body module input fault
Diagnosis step by step
Check the switch status with the pedal at rest
On the scan tool, the brake switch should read 'released' with your foot off the pedal. If it reads 'applied' and the lights are on, the signal is real; if the lights are off but the PCM still reads 'applied', look at the wiring to the PCM.
Tools: OBD-II scanner
Unplug the switch
Disconnect the switch connector with the key on. If the brake lights go out and the PCM reads 'released', the switch is stuck closed or its plunger isn't being depressed; if the lights stay on, voltage is reaching the circuit from somewhere else.
Tools: OBD-II scanner, Flashlight
Check for back-feed from lamps and trailer wiring
Unplug the trailer module and swap any aftermarket LED brake bulbs back to standard bulbs. Some LED bulbs and tow modules can feed voltage back into the brake circuit, which the PCM then reads as a pressed pedal.
Tools: Screwdriver
Measure the switch contacts
With the connector unplugged, the brake light contacts should be open with the plunger pressed in (pedal at rest) and closed when it's released. Continuity in both positions means the switch is stuck.
Tools: Multimeter
Replace and adjust
Install a new switch or pad and adjust it so the lights come on within the first few millimeters of pedal travel and go off completely when released.
Tools: Pliers, Screwdriver
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Replace pedal stopper pad | Yes | $5–$50 |
| Replace and adjust brake switch | Yes | $50–$180 |
| Repair pedal return spring or pivot bushing | No | $80–$250 |
| Repair shorted signal wire | No | $100–$300 |
| Recharge or replace battery drained by stuck lights | Yes | $0–$250 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Chevrolet | 2 | Avalanche, Cobalt |
|---|
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Depends
Emissions testing is only affected if P0573 turns on the check engine light, which varies by vehicle. Brake lights that never go out are a safety-inspection failure in states that inspect lighting.
Frequently asked questions
Why does my car feel slow with this code?
Many vehicles have brake-override logic: if the PCM sees the brake and accelerator pressed together, it reduces engine power. With the brake signal stuck on, every press of the gas can look like that situation.
Can I just pull the brake light fuse to save my battery?
That would leave you with no brake lights at all and can disable the shift interlock or push-button start. Fix the pad or switch instead; it's usually a quick job.
What is the little pad the switch presses against?
It's a rubber or plastic bumper in the pedal arm or bracket. Over time it hardens and breaks apart, and without it the switch plunger isn't pushed in when the pedal is at rest.
The lights are off but I still get P0573. How?
Then the switch contacts that feed the lights are fine, but the PCM signal wire is receiving voltage from somewhere else, such as a short to another 12-volt wire or back-feed from aftermarket lighting. Trace that wire.