FAQ
TL;DR: If the pedal bumper falls off and leaves a 10 mm gap, the brake lights can stay on; “This is how stop automatics work.” [Elektroda, nikusert, post #16762329]
Why it matters: Continuous brake lights drain the battery, mask real braking, and may indicate unsafe pedal or switch alignment. This FAQ is for Renault Laguna II owners who ask how to fix always-on stop lights and adjust the brake-pedal switch.
Quick Facts
- Stop-light logic: pedal at rest holds the switch plunger in; pressing the pedal releases it and turns lights on. [Elektroda, andrzej20001, post #16762286]
- Missing pedal grommet/bumper can create about a 10 mm shortfall, leaving the switch unpressed. [Elektroda, FINIX_47, post #16762073]
- Some switches have a ratcheting self-adjust spindle; pull it out before refit for correct set-back. [Elektroda, nikusert, post #16761911]
- With engine off, vacuum assist depletes after roughly 3–4 pedal presses; pedal then hardens. [Elektroda, FINIX_47, post #16762395]
- If unsure or pedal geometry seems wrong, get professional brake service immediately. [Elektroda, andrzej20001, post #16762401]
How does the Renault Laguna II brake‑light switch actually work?
At rest, the pedal holds the switch plunger in, keeping lights off. Pressing the pedal releases the plunger and closes the lamp circuit. This “normally closed when released” behavior often confuses owners during diagnosis. “This is how stop automatics work.” [Elektroda, nikusert, post #16762329]
Why are my stop lights on all the time after the pedal protector fell off?
The missing grommet shortens the effective pedal height by about 10 mm, so the plunger never gets pressed. The switch then reads “brake applied” continuously. Replace the pedal bumper or an equivalent spacer and recheck the switch engagement. [Elektroda, FINIX_47, post #16762073]
How do I adjust the brake‑light switch on Laguna II?
Some switches self‑set. Pull the spindle outward until it clicks. Fit the switch in its socket. Release the pedal so the plunger sets the gap. This ratchet action prevents light braking or constant lights. 1. Pull spindle. 2. Install switch. 3. Release pedal. [Elektroda, nikusert, post #16761911]
What is the ‘servo’ sound I hear when pumping the brake with the engine off?
That is the brake booster (servo) exhausting stored vacuum. After several presses, assist fades and the pedal stiffens. The behavior is normal during diagnosis and helps confirm vacuum integrity without starting the engine. [Elektroda, nikusert, post #16762399]
How many pedal presses should it take for the pedal to go hard with ignition off?
Expect roughly 3–4 presses before the pedal firms up as vacuum assistance depletes. A much higher or lower count suggests leaks or abnormal booster reserve. “Sounds like a mattress pump” accurately describes the exhaust noise. [Elektroda, FINIX_47, post #16762395]
Could misadjustment cause dragging brakes or premature wear?
Yes. If the switch or pedal stop leaves the pedal slightly applied, the system can preload and cause gradual brake drag. As one expert notes, ensure it is not pressed lightly, or wheels may start braking over time. [Elektroda, nikusert, post #16761911]
Which part should I inspect first when the stop lights won’t go out?
Inspect the pedal rubber/nylon bumper that contacts the switch, then the switch plunger alignment. A missing or displaced bumper creates a gap and leaves lights on. Restore the bumper before adjusting the switch. [Elektroda, FINIX_47, post #16762073]
Is there any adjustment on every Laguna II stop‑light switch?
No. Some switches push fully home without a separate screw, while others use a ratcheting spindle. If the design lacks adjustment, fix pedal geometry first, then replace the switch if necessary. [Elektroda, andrzej20001, post #16762207]
What’s the safe approach if the pedal feels wrong or geometry changed?
Do not drive until inspected. A mislocated pedal or incorrect free play risks poor braking and warning‑light confusion. “Have these brakes repaired in the workshop! This is not a joke!” [Elektroda, andrzej20001, post #16762401]
What is the brake‑light switch in simple terms?
It’s a small plunger‑type electrical sensor on the pedal bracket that turns the brake lamps on when released by the pedal. When the pedal returns and presses the plunger, it turns the lamps off. [Elektroda, andrzej20001, post #16762286]
How do I test the switch quickly without tools?
With ignition on, push the plunger manually. Lights should go off when depressed and on when released. If behavior is opposite or intermittent, replace or adjust the switch and check the pedal bumper. [Elektroda, nikusert, post #16762329]
My pedal has free play before the brakes bite. Is that normal?
Some free play is typical, but it must not hold the switch open unintentionally. Verify the bumper is present and the plunger is fully depressed at rest after self‑adjustment. [Elektroda, FINIX_47, post #16762395]
Can I drive while my stop lights stay on due to the switch?
Avoid driving. Constant brake lamps obscure real braking to drivers behind and drain the battery. Fix the pedal bumper and adjust or replace the switch first. [Elektroda, andrzej20001, post #16762401]
What tools or parts might I need for this repair?
You may need a replacement pedal bumper/grommet, a new stop‑light switch if worn, and basic trim tools. Visual confirmation and correct alignment matter more than special equipment for this task. [Elektroda, andrzej20001, post #16762207]
What edge case should I watch for after refitting the bumper?
If the switch is over‑extended, it may not self‑retract. Pull the spindle to reset the ratchet, refit, and let the pedal set the gap again. [Elektroda, nikusert, post #16761911]
