Brake lights constantly on?
- Thread starter rwh963
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OopsIBrokeIt
Member
95% chance your brake light switch has failed.
Replace it and you should be back to normal.
Replace it and you should be back to normal.
nighttime. decided to test the brake lights. turn on ignition, brake lights are on (don't recall if third light is on). pulled the switch, worked the plunger, seemed to work properly with ignition off. put switch back in, worked normal with ignition off. so, switch works normal with ignition off, not so with ignition on.
Here is another option, there is a green tab on your brake pedal arm, check to see if it is there? Or feel with your hand where the brake switch meets the brake pedal arm. It is a plastic piece that is notorious for breaking. Most Asian cars have them and they break. You can get a replacement, which cost about 8-15 buck that will eventually fail again or a cheap fix of a coin, penny or nickel and tape it in place for a temporary fix. I have fixed these in Toyotas, Lexus, Nissans and Honda.
Check your floor mat for green pieces.
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Check your floor mat for green pieces.
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AudiQU4TTRO
Junior Member
Let us know what you find.
I have seen this issue quite a bit and usually its just the brake light switch under the brake pedal. You may be able to get under there and just wiggle the connector for them to go off, but they will still work. Just won't be on constaly.
Hopefully its something simple like that.
I have seen this issue quite a bit and usually its just the brake light switch under the brake pedal. You may be able to get under there and just wiggle the connector for them to go off, but they will still work. Just won't be on constaly.
Hopefully its something simple like that.
I’m assuming when you pulled the switch, you still had it connected with the wire harness. If it worked when you tried it and was fine ignition off, good. You placed the switch back to its original location it was fine. You start the truck the lights come on.
Do the tail lights stay on after you shut down the truck?
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yes, switch was still connected to to the wires. so, switch works like this: brake pedal off, plunger depressed. press brake, plunger released, brake lights go on.
with ignition off, switch worked normal. with ignition on, brake lights constantly on weather brake on or off. must be something faulty in the switch. original, with 230k miles. i can grab one for $30 at the dealer. i'll try that route.
with ignition off, switch worked normal. with ignition on, brake lights constantly on weather brake on or off. must be something faulty in the switch. original, with 230k miles. i can grab one for $30 at the dealer. i'll try that route.
wow, thx for that. i think the fastest way to check is to grab a new one for $30 and see if that corrects this issue.
Jakeepoo3
New member
No problem. I may have misunderstood your post I reckon. The switch activates and deactivates via ignition switch without touching the pedal. Possibly the contact or spring is at fault..
Jakeepoo3
New member
Do you understand the diagram of the circuit the switch is on that I posted? It tells you everything you need to know. I would have told you it probably wasn't the switch since it was actually working but kind of in reverse. It literally takes a couple minutes to test it for continuity while pressed and depressed that would have saved time and you buying parts. Notice the circuit includes a relay that interacts with the stop switch when the ignition is turned!! Do you have a multimeter and a test light. They cost less than parts and you can diagnose pretty much anything with 15$ in simple tools. Most the time it's not even the part but something simple within the circuit.
no loss of time and money. was going by there anyway, and can return it without an issue, even though it was only $30 for a switch that has been used many times over the last 230k miles, sop maybe i'll just keep it.
it literally may have taken you a couple of minutes, but i'm not familiar with the procedure, so first time usually takes longer.
i do have a multimeter (and possibly a test light).
"something simple within the circuit": care to share what you're thinking?!
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Jakeepoo3
New member
I understand. I learned the first time also. It pays off big time! First check the fuses I circled visually. There is a relay that I suspect is the issue circled. You can test it with the tools I mentioned if you like. Do you hear a click with the ignition on but not started when you touch the pedal? That's the sound of an energized relay. That doesn't mean its not bad but you can test it further like I said. Use a test light or multimeter to check for battery voltage at the stop switch and check your ground there also with test light. Power to ground. Use the diagram to find the proper terminals to test. Hollar back young one!
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ok, so you suspect the relay is the fault, not the switch. is this relay highly visible and easy to access/exchange? would this also trigger VSC dash lights?
may be circumstantial, but last June 2021, i had the rear brakes completely redone. also, sometime last summer i had someone first tell me the brake lights were on (someone recently told me the same again). would brake work trigger this issue in any way (probably not, mechanical vs electrical)?
i also just had an inspection done in december 2021. no mention of brake lights being an issue.
just put the old switch back. hold onto the new one for now. do want to resolve this issue, dangerous if the lights are not indicating stopping, and cause for police stop as well.
relay part number?
thx
may be circumstantial, but last June 2021, i had the rear brakes completely redone. also, sometime last summer i had someone first tell me the brake lights were on (someone recently told me the same again). would brake work trigger this issue in any way (probably not, mechanical vs electrical)?
i also just had an inspection done in december 2021. no mention of brake lights being an issue.
just put the old switch back. hold onto the new one for now. do want to resolve this issue, dangerous if the lights are not indicating stopping, and cause for police stop as well.
relay part number?
thx
according to jakeepoo3 you are incorrect!
Jakeepoo3
New member
Haha well if the switch actually works the only problem there would be the adjuster to set the plunger in the correct position. Yes, the stop lamp switch is an input to the skid control ECU.
Well, I’m going to retract what I said earlier. It is very odd that it happen when the ignition is on but not when it is off
If the wire diagram someone posted above is correct, you have power coming from the battery and from the ignition. Makes me wander if something has broke inside the switch which the power from the ignition going into the switch is completing the circuit.
I’m not one to throw money at a problem in hopes for a fix. But $30 is enough for me to take a shot at a new switch.
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you may have missed the update, but i did buy a new switch, same result. the suggestion is the relay is bad, so i suppose with the ignition on, but brake pedal not engaged, electricity is flowing to the brake lights.
i believe with the ignition off, the brake lights get their electricity directly from the battery. with ignition on, they get their power through that system.
maybe teach can clarify this thinking.
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