What does it mean?
P1574 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Stoplamp Switch Circuit Malfunction .
Symptoms
- Brake lights stay on all the time, or do not come on when the pedal is pressed
- Cruise control cannot be engaged, or does not cancel when the brake is applied
- Selector lever will not come out of Park on many automatic vehicles
- Check engine light on, often with ABS or traction codes as well
- Torque converter lock-up behaviour changes and the transmission feels different
- Battery may go flat overnight when the brake lights remain lit
Likely causes
- Brake light switch out of adjustment after pedal, booster or master cylinder work
- Crumbled or missing pedal stopper pad, which lets the switch stay closed with the pedal released
- Worn internal contacts in the brake switch
- Blown brake light fuse or a poor ground at the rear lamp clusters
- Corroded connector at the switch, which sits in a dusty area above the pedal
- Chafed or shorted wiring in the brake circuit, sometimes caused by trailer wiring added later
- Faulty brake switch input inside the control module
How to fix it
- Check the brake lights physically before anything else, both released and pressed
- Confirm the brake light fuse and inspect the rear bulb holders and grounds
- Look at the pedal stopper pad; a perished or missing pad is a very common cause and is inexpensive to fix
- Watch the brake switch status in live data while an assistant presses and releases the pedal
- Measure switch continuity in both positions and check the adjustment against specification
- Inspect the connector and wiring for corrosion, chafing and any added trailer wiring splices
- Adjust or replace the switch, then clear the code and confirm cruise control and shift interlock work correctly