Brake/ABS INOP/Low Trac Light

[willasc]

Got a lesson in 4th gen Fbody brake system today. I have been having issue with my car's Brake light on with the ABS INOP/Low Trac Light blinking at the same time (I do not have ASR). If brake is being apply at the same time, the ABS would modulate. Which is somewhat annoy and at the wrong time, could increase stopping distance. The issue has gone on for a while, but never longer than a few seconds at a time until last time. So with some help, I finally tracked down the issue and fixed the problem. I thought I'd share it with my fellow Fbody family:

There are 4 main causes for this issue:

Third Brake Light Bulb out.

Bad ground wire for ABS (located around shock tower)

Kinked or leaky vaccum hose

Bad wire connection between vehicle speed sensor/bad sensor

In my case, it was the last one. When my axle was swapped, the left the old junkyard sensor in and connected to the car, apparently the sensor has been acting up. I swapped out the sensor with my car's original, went into Tech II to check for ABS DTC and no code, good to go! No more blinky lights.

Just thought I'd share it you guys in case similar pops up for you guys.

[meissen]

Good post, good information too.

[CHMLEON]

I would have never guessed that a 3rd brake outage would cars that.

Thanks

[silver6_maro]

my abs inop light has been on ever since I rebuilt it a few years ago. Im so used to it now, and was tempted to just pull the bulb in the gauge to make it go away when i put white gauges in. I didnt

Ill have to look into some of these problems, thanks man...

[archemedes]

I would have never guessed that a 3rd brake outage would cars that.

Thanks

no kidding sounds like a screw up in engineering to me

[02hawk796]

My '95 S10 has chebby engineered ABS, it doubles the stopping distance - of course when I need fast braking in the worst way. Several chebby service clowns tried to convince me that the purpose of ABS systems is to increase the stopping distance, which only served to tell me how clueless they are (or how bad of liars). Anyhow, just disconnected one of the sensor plugs and the ABS light stays on all the time and I stop in half the distance, even locked up all 4 tires once.

I was getting tired of using the curb/grass/sidewalk to stop, have not needed that since my "correction".
Since I worked on the original production ABS in the Boeing 747's, the thought that it should double the stopping distance would have implied that our runways are twice as long now!!

[JoeliusZ28]

yep 3rd brake can cause that. speaking of this though i do randomly get an ABS light once in a while.

[meissen]

Same here, Joel. Although mine started ever since I did that accidental chirp into Reverse on Woodward when I meant to put it into Neutral and floor it, and accidentally hit Reverse and floored it in reverse while I was going a good 40 mph... Maybe it's my 3rd brake light?

[JoeliusZ28]

Same here, Joel. Although mine started ever since I did that accidental chirp into Reverse on Woodward when I meant to put it into Neutral and floor it, and accidentally hit Reverse and floored it in reverse while I was going a good 40 mph... Maybe it's my 3rd brake light?

8-O

wow nothing broke?

[meissen]

Just my ego. Needless to say I was embarassed as hell pulling into Auto Euro with Craig and a few other guys just shakin their head, Angie was laughin at me too

[archemedes]

My '95 S10 has chebby engineered ABS, it doubles the stopping distance - of course when I need fast braking in the worst way. Several chebby service clowns tried to convince me that the purpose of ABS systems is to increase the stopping distance, which only served to tell me how clueless they are (or how bad of liars). Anyhow, just disconnected one of the sensor plugs and the ABS light stays on all the time and I stop in half the distance, even locked up all 4 tires once.

I was getting tired of using the curb/grass/sidewalk to stop, have not needed that since my "correction".
Since I worked on the original production ABS in the Boeing 747's, the thought that it should double the stopping distance would have implied that our runways are twice as long now!!

lol it's designed to make you safer by making it harder to stop are they actually that dumb? I wen to gm's tech training for that, and they never told us that

[1BADAIR]

[quote=02hawk796]My '95 S10 has chebby engineered ABS, it doubles the stopping distance - of course when I need fast braking in the worst way. Several chebby service clowns tried to convince me that the purpose of ABS systems is to increase the stopping distance, which only served to tell me how clueless they are (or how bad of liars). Anyhow, just disconnected one of the sensor plugs and the ABS light stays on all the time and I stop in half the distance, even locked up all 4 tires once.
[quote=02hawk796]

chevy trucks are known for this issue. the wheel speed sensors get corrosion under them. Take the sensors out and clean under them
ABS does increase stopping distance. ABS isn't intended to stop you faster. Its is meant to stop you while mantaining control.
I worked many years with engineers testing ABS and active stability systems for ford.

[02hawk796]

[QUOTE=1BADAIR][quote=02hawk796]My '95 S10 has chebby engineered ABS, it doubles the stopping distance - of course when I need fast braking in the worst way. Several chebby service clowns tried to convince me that the purpose of ABS systems is to increase the stopping distance, which only served to tell me how clueless they are (or how bad of liars). Anyhow, just disconnected one of the sensor plugs and the ABS light stays on all the time and I stop in half the distance, even locked up all 4 tires once.

chevy trucks are known for this issue. the wheel speed sensors get corrosion under them. Take the sensors out and clean under them
ABS does increase stopping distance. ABS isn't intended to stop you faster. Its is meant to stop you while mantaining control.
I worked many years with engineers testing ABS and active stability systems for ford.

Properly designed and functioning ABS does NOT increase stopping distance, but decreases stopping distance. The fastest method of stopping is threshold braking, braking with the max force available without breaking traction ("skidding"). If traction is lost, brief release of the brake (to allow tires to regain traction) and then re-application of the threshold force is done, which is called "pumping" the brake.
The ABS purpose is to mechanically pump the brakes, controlled by the computer, and thereby maintain absolute threshold braking with faster pump cycling than is humanly possible.
Proper ABS technology will decrease stopping distance, without regard to road/friction surface or it's friction coefficient. Perhaps whatever ford bozo taught your class really got one over on you.

One side effect of proper threshold braking, as well as rapid-cycle-pumping ABS, is that because each method maintains traction and includes intermittent release of brake pressure, steering control is also facilitated during the braking process.

With my chebby ABS Inop, I now have full control over my vehicle, and my stopping distance is almost halved. When the ABS was active, chebby was stealing away my control of the vehicle, for no beneficial purpose, and it was very dangerous - I could have easily been killed a couple times.

Maybe every person who believes ABS should increse the stopping distance should be sure to have such systems installed upon all their families' vehicles, and then eventually the gene pool will have increased it's average IQ.

Perhaps you could do us all a public service and list all of the vehicles you are aware of which increase the stopping distance by means of this improper ABS system you describe. Then the rest of us can go out to these vehicles we own and disable the ABS thereby saving the lives of our family members. That would be nice of you.

I am sure the aircraft builders would think your version of ABS would be grand - golly, we really need to have better steering ability on this STRAIGHT RUNWAY after spending the last 2 MILES of Approach LINING UP, and it only doubles our stopping distance so we'll just tell all the Airports in the world to DOUBLE YOUR RUNWAY LENGTH. HAHAHAHA hahahaha heh hahaha. Sorry, I really think that the ABS they developed and used in the late 60's was the legit system, and it decreased the stopping distances of their jumbo jets. In additon to Body-Tilt Steering, it was one of the best innovations of the 747.