My brake lights come on and stay on when I turn my headlights on, but work normally when headlights are off. Any idea what's causing this?

When you say brake lights do you mean the ones on the left and right? If so they are supposed to come on so people can see the back of your car at night. What your seeing is a dual filament bulb. When your headlights come on, the dim filament lights up, and when you hit the brakes, the second filament lights making it brighter.

When I turn on my headlights, the BRAKE lights come on too- the bright red, stepping on the brake, lights- not just the dim red lights. Its as if I have my foot on the brake the entire time. However, during the day, when headlights are off, my brake lights work normally so I don't believe its a problem with the brake light switch under the brake pedal.

suz325xi wrote:When I turn on my headlights, the BRAKE lights come on too- the bright red, stepping on the brake, lights- not just the dim red lights. Its as if I have my foot on the brake the entire time. However, during the day, when headlights are off, my brake lights work normally so I don't believe its a problem with the brake light switch under the brake pedal.

Sounds like a CAN-bus issue. I'd have to go into the FSM to see what might be causing it though. BCM is probably being told from the CAN-bus that something's not right so your brake lights are coming on too when you turn on headlights.

I'd go around your vehicle with a second person and make sure *all* your lights are operating properly, including blinkers and hazards.

Cheers,
Eemrek

I looked at the FSM. It's covered in the LT section.

If it's not the Stop Lamp Switch that's defective, then most likely the only two things that could be causing it is a wiring issue in the left stalk (which has your headlights) and it's gone defective... or a general wiring electrical issue, harness for the lamps or otherwise.

Looking at the wiring diagram, all three Stop lights are on the same circuit on the other side of the SMJ. Which could mean something is "shorting" it ON when you flip your headlight switch on or something is shorting the Stop Lamp Switch on.

Cheers,
Eemrek

I have the same problem on my Nissan tiida. The break lights switchs on when I start my head lights and it is olways switched. But when I turn of head lights it works properly. If you resolved problem please message me

xtwoonamatchx wrote:When you say brake lights do you mean the ones on the left and right? If so they are supposed to come on so people can see the back of your car at night. What your seeing is a dual filament bulb. When your headlights come on, the dim filament lights up, and when you hit the brakes, the second filament lights making it brighter.

Hello friend, I think the best way to solve it would be to enter with diagnostic equipment (scanner) to read the fault memory of the BCM and also IPDM, as there must be some fault record that will help you in the circuit that must be interfering . The FSM recommends these procedures with diagnostic equipment
DATA MONITOR Displays BCM input/output data in real time.
ACTIVE TEST Operation of electrical loads can be checked by sending drive signal to them.
SELF-DIAG RESULTS Displays BCM self-diagnosis results.
I Hope have help