P0573 is what we call a "Brake Switch 'A' Circuit High" code. In plain English, this means your car's computer-the PCM-isn’t getting the right signal from the brake pedal switch. That switch is a small but important part: it tells the computer when you’re pressing the brake pedal. This signal is used for a bunch of things, like turning on your brake lights, letting you shift out of park, and making sure features like adaptive cruise control work as they should. If the PCM senses something off-like the switch stuck in the wrong position or a signal that’s too high-it’ll set this code. In many vehicles, this can also mess with cruise control and even how your transmission downshifts. So, it’s not just about the brake lights; it’s tied into several safety and comfort systems.
DTC P0573
5739
5 minutes of readingCauses and dtc P0573
From my time in the shop, I can tell you that most P0573 codes boil down to a handful of usual suspects. The brake switch is the top contender-a lot of the time, it’s either worn out, dirty, or just knocked out of position. I’ve come across switches caked in road grime, and a quick clean brought them back to life. Wiring is another area you can’t overlook. Broken wires, corroded connectors, or wires rubbing through and shorting out are all things I’ve found behind this code. Every once in a blue moon, the problem’s deeper-like a glitch in the PCM itself. Here’s what typically causes P0573 in my experience:
- Brake switch: faulty, dirty, or not lined up right
- Wiring headaches: broken, loose, or shorted wires and connectors
- Stoplamp circuit problems (the wires feeding your brake lights)
- Rarely, a PCM acting up
Symptoms and P0573 code
If you’re dealing with this code, a few signs might tip you off before you even break out the scan tool. First off, cruise control usually takes a hit-either it won’t set, or it kicks off unexpectedly. Another giveaway? Brake lights acting funny. Sometimes they won’t light up at all; other times, they’re stuck on like a Christmas display, even when your foot’s nowhere near the pedal. Trouble getting the shifter out of park is another red flag-especially in newer vehicles that rely on the brake switch to let you shift. Spot any of these? It’s time to dig in before you wind up with a bigger headache.
Diagnosis and P0573 engine code
Here’s how I’d chase down a P0573, one step at a time. I always start simple: pop in the driver’s seat, step on the brake, and see if the brake lights fire up. No lights, or lights that stick on? You’re halfway there. Next, I get up close with the brake switch itself. Sometimes it’s just knocked out of position or has some gunk on the contacts. Have a buddy watch the lights while you work the pedal-it helps narrow things down fast. If everything seems okay so far, I’ll hook up a scan tool and see what the PCM is reading from the switch. If the signal doesn’t change as you press and release the pedal, that’s a dead giveaway there’s a problem with the switch or its wiring. Don’t forget to eyeball the wiring and connectors for broken insulation, corrosion, or loose terminals-these little things can cause big headaches. Only after I’ve ruled out the basics do I start thinking about the PCM, and in all my years, that’s rarely needed. Stick to the basics first-you’ll save yourself a lot of grief and guesswork.
Common Mistakes and obd code P0573
A classic mistake I see is folks swapping out the brake switch right away, thinking that’ll solve everything-without even checking if the switch is just loose or out of adjustment. Skipping the fuse box is another one; a blown fuse or a bad relay can mimic a bad switch. I’ve lost count of how many times someone replaced the switch, only to find out a $2 fuse was the real culprit. Another trap? Ignoring the wiring. If you don’t take a good look at the wires and connectors, you risk missing frayed wires or corrosion that can throw this code. And whatever you do, don’t just clear the code and hope for the best. Find the real problem-you’ll thank yourself later.
Seriousness and P0573
Don’t shrug this one off. If your brake lights aren’t working, you’re not just risking a ticket-you’re putting everyone on the road in danger, including yourself. Cruise control not canceling when it should? That’s a recipe for disaster. And if your car won’t shift out of park, you’re not going anywhere fast. Let this problem sit and wiring issues can snowball, sometimes taking out the PCM or other important electronics. Bottom line: you want this fixed before it leaves you stranded or, worse, causes an accident.
Repair and obd2 code P0573
In most cases, the fix is pretty straightforward-swap out the brake switch or tweak its position. I’ve had plenty of jobs where just cleaning the contacts or making sure the switch is snug did the trick. If you spot damaged wires or crusty connectors, splice in fresh wiring or replace the bad plugs. Here’s a pro-tip from the garage: always double-check the stoplamp circuit and hit the fuses and relays, too. Only once you’ve ruled out the simple stuff should you even think about the PCM; replacing or reprogramming it is a last resort and rarely needed for this code.
Conclusion
When you see P0573, what you’re really dealing with is a signal problem between your brake pedal and the car’s brain. That can throw off everything from your brake lights to shifting and cruise control. I can’t stress enough how important it is to start simple-check the brake lights, then the switch, and only then move on to wiring. Leave this code alone, and you’re asking for trouble. Fix it right, and you’ll keep your ride safe and trouble-free.
