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Home / DTC / P0571 — Brake Switch A Circuit

P0571 — Brake Switch A Circuit

Detailed page for trouble code P0571.

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22,491specific
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Code

P0571

Generic P — Powertrain

Brake Switch A Circuit

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty/brake light switch (mechanical failure or internal short)
  • Open or shorted wiring between brake switch and PCM/ECM
  • Corroded, loose or damaged connector/terminal at switch or module
  • Blown fuse or poor power feed to the brake switch
  • Poor/chafe ground or shared-ground fault
  • Aftermarket modifications (alarm, remote start, trailer wiring) interfering with circuit

Symptoms

  • Cruise control disabled or immediately cancels when activated
  • ABS, traction control, or other warning lights may illuminate
  • Brake lights not illuminating or stuck ON
  • Inability to shift out of Park (shift interlock) on some vehicles
  • Unexpected engine idle or start behavior tied to brake pedal state
  • Stored P0571 and possibly related brake-switch diagnostic trouble codes

What to check

  • Connect a scan tool: read DTC(s), freeze frame and live data for brake switch input/state
  • Visually inspect brake switch, its mounting/adjustment and connector for corrosion, damage, bent pins or water intrusion
  • Verify brake lamp operation with assistant or test light (press pedal and observe)
  • Check fuses and power feed to the brake switch circuit
  • Backprobe the brake switch connector and measure voltage/continuity with pedal released and depressed
  • Backprobe the PCM/ECM input pin for the brake switch and compare to switch-side readings

Signal parameters

  • Power feed to the brake switch: battery voltage with ignition ON (~12 V) (varies by vehicle)
  • Switch output to PCM: changes state when pedal is depressed (either toggles to ground or to battery voltage depending on vehicle design)
  • Closed switch continuity: near 0 Ω (usually
  • Transition time: signal should change state promptly when pedal is moved (typically
  • No high-resistance path or intermittent pulses when the switch is in a steady position

Diagnostic algorithm

  1. Retrieve codes and freeze-frame data with a scan tool; note ignition state and vehicle speed when code set.
  2. Verify symptom: confirm brake lights change when pedal is pressed; if brake lights fail, address switch or bulbs first.
  3. Inspect switch and harness: look for physical damage, corrosion, loose pins, or aftermarket connections.
  4. Check fuses and power feed to the switch with ignition ON; replace any blown fuses.
  5. Backprobe switch connector: measure supply voltage, and switch output with pedal released and depressed. Compare to manufacturer expected logic (either voltage-to-ground or open/ground-style).
  6. Backprobe PCM/ECM brake-switch input connector to confirm the signal arrives at module and matches switch-side readings; repeat while wiggling harness to find intermittent faults.

Likely causes

  • Failing or misadjusted brake light switch
  • Intermittent connector contact or corroded terminals at the switch
  • Wiring damage (pinched, chafed, rodent chew) between switch and module

Fault status

⚠️ Status
Brake Switch A Circuit fault detected — open/short/no signal or unexpected state on the brake switch input to the PCM/ECM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

P0571

GWM P — Powertrain

- Cruise control switch circuit A fault

Brand: GWM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty/brake light switch (mechanical failure or internal short)
  • Open or shorted wiring between brake switch and PCM/ECM
  • Corroded, loose or damaged connector/terminal at switch or module
  • Blown fuse or poor power feed to the brake switch
  • Poor/chafe ground or shared-ground fault
  • Aftermarket modifications (alarm, remote start, trailer wiring) interfering with circuit

Symptoms

  • Cruise control disabled or immediately cancels when activated
  • ABS, traction control, or other warning lights may illuminate
  • Brake lights not illuminating or stuck ON
  • Inability to shift out of Park (shift interlock) on some vehicles
  • Unexpected engine idle or start behavior tied to brake pedal state
  • Stored P0571 and possibly related brake-switch diagnostic trouble codes

What to check

  • Connect a scan tool: read DTC(s), freeze frame and live data for brake switch input/state
  • Visually inspect brake switch, its mounting/adjustment and connector for corrosion, damage, bent pins or water intrusion
  • Verify brake lamp operation with assistant or test light (press pedal and observe)
  • Check fuses and power feed to the brake switch circuit
  • Backprobe the brake switch connector and measure voltage/continuity with pedal released and depressed
  • Backprobe the PCM/ECM input pin for the brake switch and compare to switch-side readings

Signal parameters

  • Power feed to the brake switch: battery voltage with ignition ON (~12 V) (varies by vehicle)
  • Switch output to PCM: changes state when pedal is depressed (either toggles to ground or to battery voltage depending on vehicle design)
  • Closed switch continuity: near 0 Ω (usually
  • Transition time: signal should change state promptly when pedal is moved (typically
  • No high-resistance path or intermittent pulses when the switch is in a steady position

Diagnostic algorithm

  1. Retrieve codes and freeze-frame data with a scan tool; note ignition state and vehicle speed when code set.
  2. Verify symptom: confirm brake lights change when pedal is pressed; if brake lights fail, address switch or bulbs first.
  3. Inspect switch and harness: look for physical damage, corrosion, loose pins, or aftermarket connections.
  4. Check fuses and power feed to the switch with ignition ON; replace any blown fuses.
  5. Backprobe switch connector: measure supply voltage, and switch output with pedal released and depressed. Compare to manufacturer expected logic (either voltage-to-ground or open/ground-style).
  6. Backprobe PCM/ECM brake-switch input connector to confirm the signal arrives at module and matches switch-side readings; repeat while wiggling harness to find intermittent faults.

Likely causes

  • Failing or misadjusted brake light switch
  • Intermittent connector contact or corroded terminals at the switch
  • Wiring damage (pinched, chafed, rodent chew) between switch and module

Fault status

⚠️ Status
Brake Switch A Circuit fault detected — open/short/no signal or unexpected state on the brake switch input to the PCM/ECM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0572 P0573 P0561 P0562 U0121
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Code

P0571

HUMMER P — Powertrain

Cruise Control Brake Switch Circuit

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty/brake light switch (mechanical failure or internal short)
  • Open or shorted wiring between brake switch and PCM/ECM
  • Corroded, loose or damaged connector/terminal at switch or module
  • Blown fuse or poor power feed to the brake switch
  • Poor/chafe ground or shared-ground fault
  • Aftermarket modifications (alarm, remote start, trailer wiring) interfering with circuit

Symptoms

  • Cruise control disabled or immediately cancels when activated
  • ABS, traction control, or other warning lights may illuminate
  • Brake lights not illuminating or stuck ON
  • Inability to shift out of Park (shift interlock) on some vehicles
  • Unexpected engine idle or start behavior tied to brake pedal state
  • Stored P0571 and possibly related brake-switch diagnostic trouble codes

What to check

  • Connect a scan tool: read DTC(s), freeze frame and live data for brake switch input/state
  • Visually inspect brake switch, its mounting/adjustment and connector for corrosion, damage, bent pins or water intrusion
  • Verify brake lamp operation with assistant or test light (press pedal and observe)
  • Check fuses and power feed to the brake switch circuit
  • Backprobe the brake switch connector and measure voltage/continuity with pedal released and depressed
  • Backprobe the PCM/ECM input pin for the brake switch and compare to switch-side readings

Signal parameters

  • Power feed to the brake switch: battery voltage with ignition ON (~12 V) (varies by vehicle)
  • Switch output to PCM: changes state when pedal is depressed (either toggles to ground or to battery voltage depending on vehicle design)
  • Closed switch continuity: near 0 Ω (usually
  • Transition time: signal should change state promptly when pedal is moved (typically
  • No high-resistance path or intermittent pulses when the switch is in a steady position

Diagnostic algorithm

  1. Retrieve codes and freeze-frame data with a scan tool; note ignition state and vehicle speed when code set.
  2. Verify symptom: confirm brake lights change when pedal is pressed; if brake lights fail, address switch or bulbs first.
  3. Inspect switch and harness: look for physical damage, corrosion, loose pins, or aftermarket connections.
  4. Check fuses and power feed to the switch with ignition ON; replace any blown fuses.
  5. Backprobe switch connector: measure supply voltage, and switch output with pedal released and depressed. Compare to manufacturer expected logic (either voltage-to-ground or open/ground-style).
  6. Backprobe PCM/ECM brake-switch input connector to confirm the signal arrives at module and matches switch-side readings; repeat while wiggling harness to find intermittent faults.

Likely causes

  • Failing or misadjusted brake light switch
  • Intermittent connector contact or corroded terminals at the switch
  • Wiring damage (pinched, chafed, rodent chew) between switch and module

Fault status

⚠️ Status
Brake Switch A Circuit fault detected — open/short/no signal or unexpected state on the brake switch input to the PCM/ECM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0572 P0573 P0561 P0562 U0121
Repair manuals

Manual library for HUMMER

138

Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HUMMER

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Code

P0571

LAND ROVER P — Powertrain

Failure in the brake switch circuit of the control of speed

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty/brake light switch (mechanical failure or internal short)
  • Open or shorted wiring between brake switch and PCM/ECM
  • Corroded, loose or damaged connector/terminal at switch or module
  • Blown fuse or poor power feed to the brake switch
  • Poor/chafe ground or shared-ground fault
  • Aftermarket modifications (alarm, remote start, trailer wiring) interfering with circuit

Symptoms

  • Cruise control disabled or immediately cancels when activated
  • ABS, traction control, or other warning lights may illuminate
  • Brake lights not illuminating or stuck ON
  • Inability to shift out of Park (shift interlock) on some vehicles
  • Unexpected engine idle or start behavior tied to brake pedal state
  • Stored P0571 and possibly related brake-switch diagnostic trouble codes

What to check

  • Connect a scan tool: read DTC(s), freeze frame and live data for brake switch input/state
  • Visually inspect brake switch, its mounting/adjustment and connector for corrosion, damage, bent pins or water intrusion
  • Verify brake lamp operation with assistant or test light (press pedal and observe)
  • Check fuses and power feed to the brake switch circuit
  • Backprobe the brake switch connector and measure voltage/continuity with pedal released and depressed
  • Backprobe the PCM/ECM input pin for the brake switch and compare to switch-side readings

Signal parameters

  • Power feed to the brake switch: battery voltage with ignition ON (~12 V) (varies by vehicle)
  • Switch output to PCM: changes state when pedal is depressed (either toggles to ground or to battery voltage depending on vehicle design)
  • Closed switch continuity: near 0 Ω (usually
  • Transition time: signal should change state promptly when pedal is moved (typically
  • No high-resistance path or intermittent pulses when the switch is in a steady position

Diagnostic algorithm

  1. Retrieve codes and freeze-frame data with a scan tool; note ignition state and vehicle speed when code set.
  2. Verify symptom: confirm brake lights change when pedal is pressed; if brake lights fail, address switch or bulbs first.
  3. Inspect switch and harness: look for physical damage, corrosion, loose pins, or aftermarket connections.
  4. Check fuses and power feed to the switch with ignition ON; replace any blown fuses.
  5. Backprobe switch connector: measure supply voltage, and switch output with pedal released and depressed. Compare to manufacturer expected logic (either voltage-to-ground or open/ground-style).
  6. Backprobe PCM/ECM brake-switch input connector to confirm the signal arrives at module and matches switch-side readings; repeat while wiggling harness to find intermittent faults.

Likely causes

  • Failing or misadjusted brake light switch
  • Intermittent connector contact or corroded terminals at the switch
  • Wiring damage (pinched, chafed, rodent chew) between switch and module

Fault status

⚠️ Status
Brake Switch A Circuit fault detected — open/short/no signal or unexpected state on the brake switch input to the PCM/ECM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0572 P0573 P0561 P0562 U0121
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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Keep it short and practical. Up to 500 characters.
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Code

P0571

MERCEDES-BENZ P — Powertrain

Cruise Control/Brake Switch A Circuit Malfunction

Brand: MERCEDES-BENZ
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty/brake light switch (mechanical failure or internal short)
  • Open or shorted wiring between brake switch and PCM/ECM
  • Corroded, loose or damaged connector/terminal at switch or module
  • Blown fuse or poor power feed to the brake switch
  • Poor/chafe ground or shared-ground fault
  • Aftermarket modifications (alarm, remote start, trailer wiring) interfering with circuit

Symptoms

  • Cruise control disabled or immediately cancels when activated
  • ABS, traction control, or other warning lights may illuminate
  • Brake lights not illuminating or stuck ON
  • Inability to shift out of Park (shift interlock) on some vehicles
  • Unexpected engine idle or start behavior tied to brake pedal state
  • Stored P0571 and possibly related brake-switch diagnostic trouble codes

What to check

  • Connect a scan tool: read DTC(s), freeze frame and live data for brake switch input/state
  • Visually inspect brake switch, its mounting/adjustment and connector for corrosion, damage, bent pins or water intrusion
  • Verify brake lamp operation with assistant or test light (press pedal and observe)
  • Check fuses and power feed to the brake switch circuit
  • Backprobe the brake switch connector and measure voltage/continuity with pedal released and depressed
  • Backprobe the PCM/ECM input pin for the brake switch and compare to switch-side readings

Signal parameters

  • Power feed to the brake switch: battery voltage with ignition ON (~12 V) (varies by vehicle)
  • Switch output to PCM: changes state when pedal is depressed (either toggles to ground or to battery voltage depending on vehicle design)
  • Closed switch continuity: near 0 Ω (usually
  • Transition time: signal should change state promptly when pedal is moved (typically
  • No high-resistance path or intermittent pulses when the switch is in a steady position

Diagnostic algorithm

  1. Retrieve codes and freeze-frame data with a scan tool; note ignition state and vehicle speed when code set.
  2. Verify symptom: confirm brake lights change when pedal is pressed; if brake lights fail, address switch or bulbs first.
  3. Inspect switch and harness: look for physical damage, corrosion, loose pins, or aftermarket connections.
  4. Check fuses and power feed to the switch with ignition ON; replace any blown fuses.
  5. Backprobe switch connector: measure supply voltage, and switch output with pedal released and depressed. Compare to manufacturer expected logic (either voltage-to-ground or open/ground-style).
  6. Backprobe PCM/ECM brake-switch input connector to confirm the signal arrives at module and matches switch-side readings; repeat while wiggling harness to find intermittent faults.

Likely causes

  • Failing or misadjusted brake light switch
  • Intermittent connector contact or corroded terminals at the switch
  • Wiring damage (pinched, chafed, rodent chew) between switch and module

Fault status

⚠️ Status
Brake Switch A Circuit fault detected — open/short/no signal or unexpected state on the brake switch input to the PCM/ECM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0572 P0573 P0561 P0562 U0121
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

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+100 karma for a short comment :)
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Code

P0571

SEAT P — Powertrain

Brake switch - circuit fault

Brand: SEAT
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty/brake light switch (mechanical failure or internal short)
  • Open or shorted wiring between brake switch and PCM/ECM
  • Corroded, loose or damaged connector/terminal at switch or module
  • Blown fuse or poor power feed to the brake switch
  • Poor/chafe ground or shared-ground fault
  • Aftermarket modifications (alarm, remote start, trailer wiring) interfering with circuit

Symptoms

  • Cruise control disabled or immediately cancels when activated
  • ABS, traction control, or other warning lights may illuminate
  • Brake lights not illuminating or stuck ON
  • Inability to shift out of Park (shift interlock) on some vehicles
  • Unexpected engine idle or start behavior tied to brake pedal state
  • Stored P0571 and possibly related brake-switch diagnostic trouble codes

What to check

  • Connect a scan tool: read DTC(s), freeze frame and live data for brake switch input/state
  • Visually inspect brake switch, its mounting/adjustment and connector for corrosion, damage, bent pins or water intrusion
  • Verify brake lamp operation with assistant or test light (press pedal and observe)
  • Check fuses and power feed to the brake switch circuit
  • Backprobe the brake switch connector and measure voltage/continuity with pedal released and depressed
  • Backprobe the PCM/ECM input pin for the brake switch and compare to switch-side readings

Signal parameters

  • Power feed to the brake switch: battery voltage with ignition ON (~12 V) (varies by vehicle)
  • Switch output to PCM: changes state when pedal is depressed (either toggles to ground or to battery voltage depending on vehicle design)
  • Closed switch continuity: near 0 Ω (usually
  • Transition time: signal should change state promptly when pedal is moved (typically
  • No high-resistance path or intermittent pulses when the switch is in a steady position

Diagnostic algorithm

  1. Retrieve codes and freeze-frame data with a scan tool; note ignition state and vehicle speed when code set.
  2. Verify symptom: confirm brake lights change when pedal is pressed; if brake lights fail, address switch or bulbs first.
  3. Inspect switch and harness: look for physical damage, corrosion, loose pins, or aftermarket connections.
  4. Check fuses and power feed to the switch with ignition ON; replace any blown fuses.
  5. Backprobe switch connector: measure supply voltage, and switch output with pedal released and depressed. Compare to manufacturer expected logic (either voltage-to-ground or open/ground-style).
  6. Backprobe PCM/ECM brake-switch input connector to confirm the signal arrives at module and matches switch-side readings; repeat while wiggling harness to find intermittent faults.

Likely causes

  • Failing or misadjusted brake light switch
  • Intermittent connector contact or corroded terminals at the switch
  • Wiring damage (pinched, chafed, rodent chew) between switch and module

Fault status

⚠️ Status
Brake Switch A Circuit fault detected — open/short/no signal or unexpected state on the brake switch input to the PCM/ECM.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0572 P0573 P0561 P0562 U0121
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

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