Hi all,

Before anyone mentions any fixes, here's what's already been done:
Replaced all calipers other than pass front
Bled calipers at all four ends (steady stream of fluid)
Replaced rotors and pads in rear
Checked rotors and pads in front (they were done less than a year ago)
Replaced Driver Front brake hose
Always monitored brake fluid to make sure it was never low

A few days after I replaced the rear calipers, rotors, and pads I was driving along the highway and suddenly my brake light came on. I pulled over, checked the level of the fluid and was amazed that the level hadn't dropped a drop since I filled it when I serviced the rear brakes. Why was my light on...? I get back in the car and start it up...no brake light. So I merge back onto the highway and about a mile later, brake light comes back on. I ignore it and cautiously make my way back home. During the drive the brakes feel completely fine, better than they ever have.

So, I assume the light is getting triggered by the parking brake. Nope. While the brake light is on, I shut the car off, then start the car up to clear the brake light. I actuate the parking brake up and down. The light works as it should, and goes off as it should. I pump the brakes for about a minute and no brake light comes on. I've even replaced the brake fluid level sensor with a used one. Absolutely no difference. The brake light NEVER comes on while I'm sitting still, it ONLY comes on after I drive about a block or two (it doesn't take much distance, but if I reverse out my garage and pull back in, the light doesn't come on...so it requires more distance than that) and STAYS on until the car is shut off.

I'm absolutely stumped. It's not the brake fluid level sensor since the issue persists with it plugged in or unplugged (and the sensor has been swapped), the brake fluid level is always full, all four sides bleed properly with no air in the system, the E-brake switch seems to be working as it should. Those are the ONLY things I can think of that'll trigger the brake light. If anyone has some kind of insight as to what's happening with my crazy brake warning light I'd sure appreciate hearing it; can't sleep at night knowing I have a brake malfunction (yet I can't find anything wrong...)

 

I know it sounds crazy, but bad battery or Alternator could be on your horizon. I'd get those checked out along with all the work you've done so far.

 

I really doubt it, I'd expect a battery light to come on. I've already gone through a belt tensioner that exploded (causing the brake light+battery light to come on). Additionally, I have a brand new alternator sitting on the shelf just in case...however like I previously mentioned, no battery light whatsoever. Just a solid brake warning light after moving a certain amount of distance.

 

I hear you man, but when the alternator went on mine batt light didn't come on, but the brake light came on....then a few miles down I lost power even though the engine was still turning...petal to the floor I barely got it into the drive of the next gas station and it cut out. Batt light was on on only after the engine died from no power to the coils...

 

Interesting. I am however able to turn off the car and start it back up to clear the brake light. I've even sat there at idle for about 30 minutes then revv'd it at about 2k RPM for 5 minutes and absolutely no brake warning light. It only comes on when I start to actually move (and stays on). Still pointing to alternator?

I'm not trying to discredit your experience at all. I'm just attempting to keep from doing the alternator for as long as possible. I've seen where it is...lol

 

The only way to know for sure is to get the alternator tested...then you can rule that out as being the problem. Otherwise it's just speculation. But it wouldn't be the first time a Nissan with a brake light on ended up being an electrical problem.

 

Even though it may seem that I didn't want it to be the alternator...I kinda did. Tested it at Autozone and it's good. Steady 14.1v at idle. Damnit.

So check this out, I unplug the brake fluid level sensor after a restart. No brake light comes on the dash, wtf? So, I go for a drive. Brake light still comes on after a block or two. I go back home to the garage and plug the connector for the brake fluid level back in. Light still on. So, I disconnect the connector again and plug it into the old brake fluid level sensor (without the sensor being in the reservoir). Light still on. I get a magnet and stick it to the sensor, light still on. Take the magnet off, light still on. Hmph.

So I disconnect the parking brake switch sensor connector. Light still on. WTF? So I disconnect the brake fluid level sensor (while the parking brake switch sensor is disconnected) and...LIGHT...STILL...ON.

This has seriously chapped/triggered me. There are ZERO issues with the brake system, yet the brake light (and only the brake light) is on the dash? Uhh...what? Every time I drive the car I have an immense amount of panic because I don't want to put anyone else on the road at risk if my brakes go out but A) I don't have another DD and B) I can't find ANYTHING wrong with the braking system: pads are good, rotors are good, 3/4 of the calipers are brand new, there's absolutely no air at any of the 4 corners, brake fluid is fresh DOT4, brand new brake hose on the driver front.

Desperately asking for help before this car gives me copious amounts of grey hairs.



EDIT: Follow up. So, I found the ABS fuse on the passenger side (forgot about that fuse box). Bingo. It turns on the BRAKE light when disconnected. I assume one of my four wheel sensors are bad and/or the cursed control module. Perhaps I knocked some debris loose during the previous brake job and wiped out a wheel sensor. Oops.

 

I've had this same issue with my 03' over the last few months. All the brake system components are OK, but the light stays on 80% of the time whether or not the parking brake is engaged. Its harmless but it drives me nuts.

 

As long as youre 128% sure that there are no leaks nor air in the lines, its harmless. Ive monitored the brake level after every trip for weeks. This is the only reason why I'm still driving it. Otherwise it would be parked and worked on. If theres one thing i dont mess around with...its the brake warning light.

On another note, its stupid that the ABS module would trip the brake light. Absolutely dumb. But it does. Its the ONLY other thing besides the parking brake and low fluid level that would trip the light...errrr. ABS light? Sure! Brake light? Nah. Thats a bit excessive.