Brake Fluid Sensor Stuck?


#1

This last week my brake fluid light comes on my 2006 Ram 1500 but my fluid level in the reservoir is at max…fluid is a yellowish color when I look at it out of reservoir (looks darker in the reservoir).

If I unplug the sensor to the reservoir, the light still stays on which puzzled me, but I’m not honestly sure what I’m hoping to see happen. I am no positive if I’m due for a brake job, but the pads still looked to be good to me (not sure if that could trip the sensor). Any suggestions on where to start?


#2

@sethmac

Are you sure that the warning light is for Low Fluid and not a Brake System or ABS warning light?

Do you have ABS?
CSA


#3

I have a separate ABS light that is not on. The light is the same light that comes on when the parking brake is on, but from the manual it also appears to be a light that may indicate a brake system issue.


#4

@sethmac

Does the parking brake pedal pop ALL the way up, when you release?


#5

@sethmac
"The light is the same light that comes on when the parking brake is on, but from the manual it also appears to be a light that may indicate a brake system issue."

Using the manual can you find mention of a Low Brake Fluid warning symbol/message?
CSA


#6

No sign of low brake fluid. I’ll go through one more time to make sure. Yes, parking brake pops out.


#7

If you hold the parking brake release with on hand and pull up on the parking brake lever with the other and the light goes out, either your parking brake needs adjusting or your parking brake mechanism or cables are corroded.


#8

Besides the above ideas which are where to start, on some cars the warning light system will flag a failing alternator as a brake problem. They do that b/c the alternator warning light might be burned out, and they want to alert the driver to a situation that needs to be immediately addressed. Not sure if that applies to you vehicle though. If the alternator warning light comes on with the key in on and the engine not started, that’s unlikely. But if the alternator warning light doesn’t seem to ever come on, worth considering.


#9

+1 to oldtimer’s post. I’d add to the list a possible need for an adjustment to (or replacement of) the button that the parking brake presses to notify the system that the brake has been disengaged.


#10

@GeorgeSanJose

“on some cars the warning light system will flag a failing alternator as a brake problem. They do that b/c the alternator warning light might be burned out, and they want to alert the driver to a situation that needs to be immediately addressed.”

Which cars are these?

The only thing I can think of . . . low voltage situations can illuminate the amber abs and/or red brake warning lights

But that theory with the “alternator warning light might be burned out” . . . never heard of it

No offense intended :smiley:


#11

No worries. I get it backwards, which light triggers the other one to come on. On my Corolla anyway there’s definitely a link between the brake and alternator warning light. One always comes on as a back-up indicator when the other is triggered, but I can’t remember which one is the trigger and which is the back-up. I’ll look it up and report back.


#12

On mine the only thing that triggers that light is low fluid or the parking brake pedal being depressed. Try pulling up on the parking brake pedal to see if that turns it off. Otherwise it could be a faulty switch. Now the sensor for the low fluid is in the master cylinder and if that is faulty, the master has to be replaced. Happened to me.


#13

George writes …

"on some cars the warning light system will flag a failing alternator as a brake problem. They do that b/c the alternator warning light might be burned out, and they want to alert the driver to a situation that needs to be immediately addressed."

@db4690 writes …

Which cars are these?

The only thing I can think of . . . low voltage situations can illuminate the amber abs and/or red brake warning lights

But that theory with the “alternator warning light might be burned out” . . . never heard of it

See the attached diagram for how it works on a 1992 Toyota Corolla. See how the brake light will come on if the alternator fails?


#14

That should help to confuse the OP, the old Asian cars did that but this is not an old Asian car.


#15

Sorry if that diagram confuses the OP. That’s not my intention. It’s intended to provide some clarity for the interested gear heads among us. If the OP objects to that information being provided, the OP should let us know. I can easily delete it.


#16

It’s not the diagram but the suggestion that the alternator is failing with the brake system warning light on instead of the generator warning light.


#17

@GeorgeSanJose

Thanks for that wiring diagram :grin:


#18

You are most welcome @db4690 , glad you found it useful.


#19

Is that brake/alternator warning light method commonly used on cars as recent as the early 90’s not used on any newer vehicles then @Nevada_545 ? As I recall my old 1970’s VW Rabbit used that method too. What date did the manufacturers stop using it, and why did they stop using it? It seems like it has the important advantage of providing a fail-safe if the dash bulb warning light burns out and the owner doesn’t notice it.