ABS and brakes

C0577 — Brake Pedal Switch Circuit Fault

Severity: medium Drive with care, to a shop

What C0577 means

The control module reads the brake pedal switch and compares it with other inputs, such as brake pressure or pedal position. With C0577, the signal is missing, implausible or out of range. Brake lights, cruise control, the automatic transmission shift interlock and some ABS/stability functions depend on this signal.

Symptoms

  • Cruise control not working
  • Brake lights stay off or stay on
  • Shifter won't leave Park
  • ABS or stability control light on
  • Trouble starting cars that require the brake pedal to be pressed

Possible causes

  1. Failed brake light switch
  2. Switch misadjusted or out of position at the pedal
  3. Open, shorted or corroded wiring near the pedal
  4. Corroded switch connector terminals
  5. Burned-out brake bulbs or poor ground
  6. Adjustable pedal assembly out of range, if equipped

How to diagnose

  1. Scan for codes and look for related ABS, brake or cruise codes
  2. Check whether the brake lights come on when the pedal is pressed and go off when released
  3. Inspect the switch for correct mounting and contact with the pedal plunger
  4. Inspect the connector and wiring at the pedal for corrosion, damage or looseness
  5. Measure supply voltage and signal at the switch with the pedal pressed and released
  6. Test the switch contacts against the manufacturer's specification
  7. Watch the brake switch status in live scan tool data
  8. Clear the code and road test after repair

Common fixes

  • Replace the brake light switch
  • Readjust the switch position
  • Repair the wiring or connector and clean the terminals
  • Restore the ground and replace burned-out bulbs
  • Replace or adjust the pedal assembly per service procedure

Questions and answers

What does C0577 mean?

It's a fault in the brake pedal switch circuit: the module isn't getting a valid signal that the pedal is pressed. The switch itself or its wiring is the most common cause.

Can I drive with C0577?

Short, careful driving is usually possible, but first check that your brake lights work. If they don't, fix it right away.

Why did my cruise control stop working?

Cruise control must cancel when you brake, so it needs a reliable switch signal. When the circuit is faulty, the system shuts off as a precaution.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.