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2009 GMC ENVOY
4.2L I6•4WD•AUTOMATIC•gas
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Repairs0Labor985Torque9299Fluid18DTC3910Battery2Maintenance0Recalls0
P1574moderate severityPowertrain

Stoplamp Switch Circuit

on 2009 GMC Envoy 4.2L I6 · 4WD

What this code means

The PCM detected a malfunction in the brake (stoplight) switch circuit. The brake switch signal is used by multiple systems including cruise control, torque converter clutch, and brake/shift interlock.

Symptoms

  • Cruise control not disengaging when braking
  • Brake lights staying on or not working
  • Transmission not downshifting when braking
  • Shift interlock not releasing
  • Check Engine Light

Common causes

  • Faulty brake light switch
  • Misadjusted brake switch
  • Blown brake light fuse
  • Damaged wiring to brake switch
  • Brake switch connector issue

Diagnostic steps

  1. Test brake light switch operation
  2. Check brake light fuse
  3. Inspect brake switch adjustment
  4. Test circuit voltage at switch connector
  5. Check brake lights for proper operation

Repair notes

Adjust or replace brake light switch. Check fuse and wiring.

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