Transmission & clutch

Brake shift interlock not working

When the interlock that requires the brake pedal before shifting out of park fails, it's almost always the brake light switch, a fuse, or the interlock solenoid itself.

Difficulty
Easy
Time
20–40 minutes to diagnose
DIY cost
$5–$30
Pro cost
$100–$350

Symptoms

  • Shifter stays locked in park even with the brake pressed firmly
  • Brake lights may be out at the same time
  • Works intermittently, sometimes needing several tries
  • Manual override slot near shifter provides a temporary workaround

Likely causes

  • CommonFaulty brake light switchThis switch, mounted near the top of the brake pedal, tells the interlock the brake is pressed; it's a common failure point.
  • CommonBlown fuseA fuse dedicated to the interlock circuit or shared with brake lights can blow and disable the system.
  • PossibleMisadjusted brake pedal or switch positionA switch that's slightly out of position may not register the pedal press correctly.
  • PossibleFailed shift interlock solenoid at the shifterThe solenoid that physically releases the shift lock can fail electrically or mechanically.
  • Less commonWiring issue between switch and solenoidDamaged or corroded wiring can interrupt the signal even with good components.

What to do

  1. Check whether the brake lights work when you press the pedal, since a shared fault often affects both.
  2. Check and replace the relevant fuse if it's blown.
  3. Try the manual shift-lock override near the shifter (check the owner's manual) to move the car if needed.
  4. Inspect the brake light switch area at the top of the brake pedal for a visibly loose or disconnected switch.
  5. Avoid relying on the manual override as a permanent solution.
  6. Have a mechanic test the brake light switch and interlock solenoid with a multimeter if fuses check out fine.
  7. Replace the faulty component once identified, then confirm normal operation.

Tools and parts

  • Fuse puller/tester
  • Multimeter (optional)
Brake light switchSearch: “brake light switch [make model year]”

When to call a pro

See a mechanic if the brake light switch and fuses aren't the issue, since testing the solenoid and wiring needs some electrical diagnosis.

Safety

Generally low risk

Generally low risk for a careful person. Stop if anything looks different from what this guide describes.

Related guides

Operator provides AI-generated troubleshooting information. It can be wrong. For safety-critical, electrical, gas, structural, medical, automotive safety, or other high-risk problems, consult a qualified professional.