Why does my emergency brake light come on at WOT?

[garolittle]

I've noticed that my brake light appears briefly upon rapid acceleration (and rapid "decceleration"). Since my emergency brake is down (yes, I checked that ) what could the problem be? Thanks.

 

[MadMaxx]

....brake fluid levels low.....?

 

[SNKEBIT]

unconscious fear????

 

[CAS]

Well, the cable could be loose, tripping the light when a lot of force (acceleration) is applied.

 

[Tom F&L GoR]

Inside the "combination valve" is a spool that makes electrical contact if the front vs. rear brake line pressure is different (i.e. if one end of the car had a brake line leak.) With low fluid, it would only come on if the brake was applied and then should stay on.

The other way the light comes on is if the parking brake switch on the handle isn't released. I don't think the cable looseness matters.

In any case, I suspect you have a wire that is grounding out upon severe car tilt.

 

[GTSJERRY]

check the brake fluid!

 

[Doc.]

I agree with checking the brake fluid. I had a BMW one time that would have the brake light come on every time I went up the ramp in my parking garage if it was low on fluid. It was fine on level ground. You could have the same phenomenon with acceleration.

doc.

 

[AviP]

Your brake fluid level is probably low. Under rapid acceleration and deacceleration, the sensor might show a low fluid level. Fluid level could be low because your brake pads are worn too. I would check the pads first before filling up. Brake fluid is very hygroscopic (absorbs water), so if you need to fill, do so from a new container. Hope this helps.

 

[Tom F&L GoR]

This is good, a little controversy hopefully solved with a little education. Section 5-17 of the service manual describes the pressure differential warning light switch as activated by umm... a pressure difference between the front and rear circuit.

"When the brake pedal is depresed and hydraulic pressure is lost in one system, the warning light switch wil activate the Red Brake Warning Light on the instrument panel."

On acceleration, there isn't any brake line pressure. Upon deceleration, it should stay either on or off, since as soon as you step on the pedal, the master cylinder is cut off from the brake lines.

It is also latching, so upon a pressure loss, it will stay lit until the repair is made. Check the brake fluid, but I don't think that's it.

 

[Viper Wizard]

Unconscious fear????

That's good!

 

[garolittle]

Thanks guys. I love this site!

 

[MadMaxx]

Garolittle: Was it the flow fluid?

Also this isn't a pressure activated issue Tom. There is a fluid level sensor in the MBC resevoir from what I remember. A simple little dummy light will illuminate if the fluid level drops beyond a certain point. If the fluid is low, but not below the line, sloshing it around will trigger it, which seems to be his issue.
If it was a pressure failure then it would indeed trigger a SES light as well as a brake light IIRC.

 

[Lawrenzo]

I had my car in to fix some loose wiring for the e-brake. The light was popping on and off similar to what you stated. Check the wire/sending unit.

 

[Tom F&L GoR]

MadMaxx, I understand there could be fluid level sensors, and I may have jumped the gun by replying based on a non-ABS car. However, looking at the 2001 parts manual, it also does not show any electrical connection at the MBC, hence I still vote for the loose wire. Garolittle, IMWTK! (Inquiring Minds Want To Know!)

 

[garolittle]

Garolittle: Was it the flow fluid?

Hey guys. I have not found a fix yet since work and family are keeping me from my Viper. My gratitude was aimed at the free advice which I will use to pursue a solution. It may be another week before I can look into the issue again but I do appreciate your help. Thanks.

 

[AviP]

Garolittle: Was it the flow fluid?

Hey guys. I have not found a fix yet since work and family are keeping me from my Viper. My gratitude was aimed at the free advice which I will use to pursue a solution. It may be another week before I can look into the issue again but I do appreciate your help. Thanks.

What everybody said and don't forget to check the pads for wear first or you could be ready for expensive rotor replacement.

 

[Greg 99ACR Red and Silver]

I vote for a loose/or dirty connection.

This happened to me long ago at the track, and the problem went away permanently.

Check this:
Unplug the cable connector to the sensor unit on the brake line T-block (on the wheel well below the fluid reservoir). Clean it or blow it out with an air gun and then plug it back in (mine was loaded with dirt). Also verify that the cable is not pulled too tightly in the harness, causing a strain on the cable (mine was).