Why is my brake light on ?

Mikessprinter

07 ncv3 170
Hi all. Seems I have a problem with my brake system . I have a 2008 sprinter without steering wheel controls. The Red brake light went on last week ,after which I checked the brake fluid , checked the ebrake. Changed the rear discs , checked the calipers to make sure they’re functioning, checked the bake pad sensors, checked the u joints on the driveshaft . Also had all the wheels balanced. And still it’s on. I have a generic scanner which I knew would tell me nothing . The vehicle brakes fine so it’s confusing. Also I don’t have a trailer or hitch. And there is no buzzer that sounds. The service manual seems to point to ebv system malfunction but I’m not sure what else to check. Any ideas would be much appreciated. Thanks gents.
 
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autostaretx

Erratic Member
In the T1N, the red "BRAKE" light on the instrument display has two meanings:
(1) Brake fluid level too low and
(2) electronic brake force distribution (EBD) malfunction

So you checked #1, but it may take a scanner to check #2

Check your owner's manual for the meaning of the displayed message.

--dick
 
The Red brake light went on last week ,after which I checked the brake fluid , checked the ebrake. Changed the rear discs , checked the calipers to make sure they’re functioning, checked the bake pad sensors, checked the u joints on the driveshaft . Also had all the wheels balanced. And still it’s on. I have a generic scanner which I knew would tell me nothing .

Any ideas would be much appreciated. Thanks gents.
Wheel balance and J-joints have nothing to do with the red brake warning light.

Why did you change the rear brake rotors?

Sounds like you should have a competent Sprinter technician diagnose and repair the Cause of your red brake warning light Concern before you drive it on public roadways shared with other motorists.
 

autostaretx

Erratic Member
Here's what the 2015 Owner's Manual has to say about the red BRAKE warning light:
(note: that it says to *not* add fluid!)

BRAKEwarning.png

--dick
 

Daystar

Member
The brake wear sensor light on an '08 is an amber dashed circle. The red light that says "Brake" comes on with low fluid, or what it thinks is low fluid. After checking all you did on my '08, I added fluid even though it was half way between Max and Min. It solved the problem.
 

Mikessprinter

07 ncv3 170
Well I’m all out off ideas. Other than swapping out the brake reservoir. Seems like the only thing that could cause the light other than a trailer is fluid. It’s always been at the full mark though. When I put it on the icarsoft it says the sensor is reading it low. Checked the wiring and all looks good. Is there any way to test the brake fluid reservoir sensor manually ? I’ve never heard of one of these crapping out so I’m still skeptical that it’s the sensor.
 

Mickyfin

Member
Have you tried resetting the brake switch?

Sent from my TA-1033 using Tapatalk
 

autostaretx

Erratic Member
The brake switch is "reset" by pressing the pedal with your hand, then pulling the plastic stalk (from the switch) that normally "follows it down" ...gently pull that shaft out until it stops. Release pedal gently.

That's a T1N procedure ("it's in the book"), but i've seen NCV3 owners report that it clears things up, too.

--dick
 

Mikessprinter

07 ncv3 170
The brake switch is "reset" by pressing the pedal with your hand, then pulling the plastic stalk (from the switch) that normally "follows it down" ...gently pull that shaft out until it stops. Release pedal gently.

That's a T1N procedure ("it's in the book"), but i've seen NCV3 owners report that it clears things up, too.

--dick
Thanks dick.

I thought that was it and just tried the procedure ( which is the same on the NCV3) but no dice. That dang light is still on.

On another note. To test the reservoir sensor I would see if there is continuity (which there shouldn’t be ifs full) but I can’t even get to the pins on it.

Any other ideas much appreciated.
 

Mickyfin

Member
Try unplugging the brake light switch, check the connector and wiring. Also, the BLS has two switches, x1 the white physical switch you just reset, and an internal communication switch which communicates to the CANbus, it's quite a cheap part to buy, replace, and swap out is easy enough to do yourself.
 

Mikessprinter

07 ncv3 170
Try unplugging the brake light switch, check the connector and wiring. Also, the BLS has two switches, x1 the white physical switch you just reset, and an internal communication switch which communicates to the CANbus, it's quite a cheap part to buy, replace, and swap out is easy enough to do yourself.
Thanks. I’m gonna try looking at those two switches better tomorrow.

In the manual it only gives two causes for the red brake light coming on without any other warnings on. Which are fluid level low , and trailer brake problem. So since I don’t have a hitch I thought the only place to look would be at the reservoir.

But it does make sense that a malfunction in the BLS would set it off too.
 

Mickyfin

Member
Replace it, it's only around $25, and easy to fit, then at least you can rule out this, but hopefully renewing the BLS will resolve your issue.
 

ptheland

2013 144" low top Passgr
So since I don’t have a hitch I thought the only place to look would be at the reservoir.
It's not the hitch itself that would be the issue, it's the trailer wiring. It's possible to have one without the other - no telling what a previous owner may have done. The van could have been built with the hitch and wiring, then the hitch was removed somewhere along the way. Or the trailer wiring could have been added in anticipation of adding a hitch - and the hitch never happened.
 

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