Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P0572 Brake Switch A Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Brake switch A is the brake light switch or its signal to the engine module. The module needs it to cancel cruise control and for brake-throttle override, stop-start, idle control and the shift interlock. As cruise control is simply switched off, CARB treats such faults as emission-neutral – usually without warning lamp. P0572 means the switch signal stays low – never pressed – although the car brakes. Ford petrol checks over 25 brake applications, Ford diesel over 40 decelerations; GM in the Saab 9-4X and 9-5 compares the input with the body module's message, 8 of 10 samples over 2 s. Cruise control is locked out; Ford shows only the wrench lamp.

Likely causes

Brake light switch faulty or misadjusted (not switching)
Brake light or switch supply fuse blown
Signal line open or shorted to ground, connector
Body or engine module

Symptoms

  • Cruise control not working
  • Brake lights not lit (depending on cause)
  • Wrench lamp (Ford), no check engine light

Repair estimate

DifficultyEasyDIY possible
Parts and labour€15–120
Time0.3–1 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

brake switchbrake light fuseswitch wiringengine control module

Related codes

P0571P0573P0504P057B

References: fordservicecontent.com, fordservicecontent.com, saabwisonline.com, saabwisonline.com.