Stop Lamp Switch Signal Malfunction
What it means
This is a Toyota-specific code; the same number may mean something different on other makes. The engine computer monitors the stop lamp (brake light) switch at the pedal, and found the signal does not change as expected between stopping and driving away, for example staying on all the time. This affects the rear brake lights and can disable cruise control.
Models covered: Toyota models, mainly 1996–2008.
Symptoms5
- Check engine light on.
- Rear brake lights stay on, or do not light when the pedal is pressed.
- Cruise control does not work or cancels by itself.
- The shift lever is hard to move out of Park on some models.
- Dead battery if the brake lights stayed on overnight.
Possible causes5
- Stop lamp switch out of adjustment or failed internally.
- Damaged or missing rubber or plastic pad that the switch presses against at the pedal, leaving the switch stuck on or off.
- Blown brake light fuse.
- Open or short in the switch wiring or connector.
- Engine computer fault (rare).
How to diagnose5
- Have someone watch the rear brake lights while you press and release the pedal.
- Inspect the switch above the pedal and confirm the pad it touches is present and intact.
- Check the brake light fuse.
- Watch the brake switch signal on a scan tool; it should change instantly with the pedal.
- Measure voltage at the switch terminals in both pedal positions.
How to fix5
- Replace a missing or damaged pedal pad.
- Replace a blown fuse after fixing the short.
- Adjust or replace the stop lamp switch.
- Repair the wiring or connector.
- Clear the codes and confirm the brake lights and cruise control work.
Repair cost
In Saudi riyals; the highlighted part is the expected range for this fault.
A pad, fuse or switch adjustment costs little; a new switch with labor is the top of the range.
Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026
Frequently asked questions
Is it dangerous to drive with P1520?
The engine is not harmed, but if the brake lights do not come on, drivers behind you cannot see you stopping, which is a real risk. Fix it quickly.
Why does the battery go flat with this code?
If the switch stays pressed because the pad is missing or it is misadjusted, the brake lights stay on after the car is off and drain the battery.
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What was wrong? (optional)
This guide is for information only and does not replace an inspection by a qualified technician. If the fault involves brakes, steering, engine temperature, electrics or refrigerant, do not attempt the repair yourself.
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