abs light stays lit on dash, what could cause this?

[DanFormulaMan]

So my 94 Firebird's ABS light is always ON, but no SES light ON. What could be the cause of this? any input would be appreciated.
Thanks Dan

[Joe 1320]

That means there is a fault in the antilock brake system. many times, it's merely a failed sensor at either front wheel hub or on top of the differential for the rear. It may be a bad harness connection, so try that first.

[Injuneer]

Do you mean the "ABS INOP" light is on? If so, Joe gave you the answer. The ABS system does not turn on the SES light, and has nothing to do with the PCM. That's why there's an "ABS INOP" light - to tell you the system isn't working. You need to scan the EBCM to get the codes for the ABS system.

[DanFormulaMan]

Can I scan the EBCM without a code reader and is there a different port than the PCM? I also have the Emergency Brake Light stuck on all the time, any relation or seperate problem?

[formula_gramps]

I also have the Emergency Brake Light stuck on all the time, any relation or seperate problem?

There sure could be a connection!

That light you are referring to as the emergency brake light, serves more than one purpose.

As I'm sure you know, it normally comes on when the e-brake is engaged. All other times, it is normally off.

If the e-brake is not engaged though, and the light comes on, it is an indication of some type of failure in the hydraulic portion of your brake system.

Like most cars today, there's really two brake systems -- one front, one rear, that can be isolated from one another.

If for example, you were to develop a leak in some portion of the rear half of your brake system, the system would detect the pressure differential between the front and rear systems, and a valve would close and prevent further fluid from bleeding out through the portion with the leak. Otherwise you'd soon be running around with no brakes at all. The "brake" light would then come on indicating there is a problem. The front brakes would remain functional in this particular example.

Right now, your brake light being on all the time is a higher priority than the ABS light. You need to chase down where the failure is and repair it, replace the lost brake fluid, and bleed the system of any air. Once this is all done, the "brake" indicator light will go out after you have hit the brake pedal with sufficient force. ( I forget how much force it takes, but as I recall it is considerable to reset the valve). Then, when the brake system is functional again, I wouldn't be surprised if that ABS light went out too.

By the way, I'm assuming this car does not have traction control (a.k.a. 4 channel system)-- is that correct?

[Injuneer]

Traction control was not available in 94. It was advertised in the dealer brochures, but was not actually sold until the 95 model year.

[formula_gramps]

I didn't know that Fred....thanks. I do remember it being listed as an option back then.

You mean to tell me I have spent all these years of driving my virtually undrivable bird in the snow, sleet, and icy New England winters lamenting the fact that I that I never sprung for traction control because I am such a cheap b****d ---- for nothing?

[DanFormulaMan]

Wow Gramps I would've never thought to look at brake fluid level chasing an electrical issue, this helps tremendously. No I don't have traction controll by the way. I will go into motoralldata and see where it takes me.
Thanks Dan

[formula_gramps]

I'll tell you something Dan, you can have the tiniest leak somewhere in the system --- so tiny that you never spot any brake fluid on the ground under the car.

I know this because that happened to me. Your bird is about the same age as mine and I ended up having to replace the lines from the engine compartment all the way back to the rear axles last year. I had a tiny pinhole in one of the lines. My only indication that something was wrong was the brake light came on.

In my case it meant the rear half of the braking system shut down, and to tell the truth -- it was not that noticable. I forget what the brake bias is front to back, for our cars, but most of it is to the front. In normal driving then, most of your stopping power is coming from the front. If you don't think the brakes feel all that different from usual, and you are going to chase down a leak, I'd start with the rear half first, because if the front system shut down, I think you'd notice the reduced stopping power right away.

On mine, the lines were pretty much rotted and ready to let go, so I decided to replace everything. This was also a good excuse to purge the entire remainder of the system and get all new brake fluid in everywhere.

One other thing: Do you hear any unusual sound when you apply the brake, such as a "groaning" sound? That's what mine did as the problem got worse, and it was coming from the master cylinder. I came to the erroneous conclusion that it was the M/C at fault and replaced it. Then, the new one groaned....LOL! Then the whole situation made me groan!

This meant I had to start looking elsewhere.......