antilock brakes not working

[ericn1300]

I drove the '92 Bravada in a snow storm the other morning and the anitlock brakes didn't seem to work. Today I took it to the packed snow covered parking lot at the high school to test it out. did repeated run ups to over 25 mph and slammed on the brakes. No antilock action or pump noise at all, brakes just lock up and I get some good slides.

The ABS light on the dash tests normal when i put the key to the start position. Now here's the weird part. I jumpered the OBDI to check for ABS codes and I heard the ABS pump run for a moment when I turned the key to the run position. No trouble codes, the ABS light just flashed a 14 nonstop which I assume is start and end of file. Encouraged by the pump noise I took it out and test drove it again. The ABS kicked in a few times, probably less than one in ten tries.

Any Ideas of where to start guys? I've never worked an an ABS system before.

[MT-2500]

Originally Posted by ericn1300

I drove the '92 Bravada in a snow storm the other morning and the anitlock brakes didn't seem to work. Today I took it to the packed snow covered parking lot at the high school to test it out. did repeated run ups to over 25 mph and slammed on the brakes. No antilock action or pump noise at all, brakes just lock up and I get some good slides.

The ABS light on the dash tests normal when i put the key to the start position. Now here's the weird part. I jumpered the OBDI to check for ABS codes and I heard the ABS pump run for a moment when I turned the key to the run position. No trouble codes, the ABS light just flashed a 14 nonstop which I assume is start and end of file. Encouraged by the pump noise I took it out and test drove it again. The ABS kicked in a few times, probably less than one in ten tries.

Any Ideas of where to start guys? I've never worked an an ABS system before.

When they do not work or ABS light is on without turning key OFF put a jumper from pin H-A for abs codes.
Was it A-B pin jump that you used for the test or A-H jump?

[ericn1300]

Originally Posted by MT-2500

When they do not work or ABS light is on without turning key OFF put a jumper from pin H-A for abs codes.
Was it A-B pin jump that you used for the test or A-H jump?

Yeah, I jumped top right to lower second from the left, A-H, and as noted above the ABS pump actuated and I read the flashing ABS light so I'm pretty sure I got it right. Is a 14 the begining and end of file for the ABS codes?

[Chris Stewart]

I think 14 is the code for ABS check, I'm at work but I'll check the book when I get home...around 3:00pm CST

[MT-2500]

Originally Posted by ericn1300

Yeah, I jumped top right to lower second from the left, A-H, and as noted above the ABS pump actuated and I read the flashing ABS light so I'm pretty sure I got it right. Is a 14 the begining and end of file for the ABS codes?

Here is the code list for ABS brakes.
http://members.troublecodes.net/crunch/92bravoant.pdf
The code should repeat there self when testing.
One long and 4 shorts pause and then repeat should be code 14.
But 4 longs and one short would be a ABS code of 41
You might double check it again.
If all else fails.
You may have to find a ABS capable scanner to check it out.
Good luck

[ericn1300]

Originally Posted by MT-2500

Here is the code list for ABS brakes.
http://members.troublecodes.net/crunch/92bravoant.pdf
The code should repeat there self when testing.
One long and 4 shorts pause and then repeat should be code 14.
But 4 longs and one short would be a ABS code of 41
You might double check it again.
If all else fails.
You may have to find a ABS capable scanner to check it out.
Good luck

yes, 1 long 4 shorts repeatedly. I think that means no codes set.

[MT-2500]

Originally Posted by ericn1300

yes, 1 long 4 shorts repeatedly. I think that means no codes set.

I am not sure one way or the other on that.
I can not find any info on no codes set.
But one thing to remember you need to check it when they are acting up without turning key off.
When you turn key off the codes will clear there self and not show up untill the code sets again.
So try to catch it in the act.
Good luck and let us know how it goes.
MT

[ericn1300]

Originally Posted by MT-2500

I am not sure one way or the other on that.
I can not find any info on no codes set.
But one thing to remember you need to check it when they are acting up without turning key off.
When you turn key off the codes will clear there self and not show up untill the code sets again.
So try to catch it in the act.
Good luck and let us know how it goes.
MT

there is no ABS light coming on, there is no codes being set. the antilock just doesn't work most of the time. the code 14 is the begining of file and the end of file just like code 12 is the begining and end of the powertrain codes. is there a way to manually exercise the pump? i think it's just sticking from lack of use or old age.

[MT-2500]

Originally Posted by ericn1300

there is no ABS light coming on, there is no codes being set. the antilock just doesn't work most of the time. the code 14 is the begining of file and the end of file just like code 12 is the begining and end of the powertrain codes. is there a way to manually exercise the pump? i think it's just sticking from lack of use or old age.

There is a relay for the abs could be sticking.
Here is a couple of pdf on pump motor problems.
All of the info I can find on it.
http://members.troublecodes.net/crunch/92abs.pdf
Good luck

[Chris Stewart]

Ya'll are doing like book shows.
The brakelight switch kinda turns the thing on, maybe it needs an adjustment. It's under the dash where the brake pedal pivots. A panel under the dash has to be removed to access it.

Brakelight switch adjustment:
The stoplamp switch will self adjust the first time the brake pedal returns to it's stop after the switch is installed.
1. Apply the brake pedal and press the switch in until it firmly seats in the clip.
*"Clicks" can be heard as the threaded portion of the switch is pushed through the clip.
2. Pull the brake pedal against the stop until the "click" can no longer be heard.

[ericn1300]

i pulled and cleaned all the connectors and swapped around some relays (not sure which would br the ABS) and took it out for a test drive. things are thawing out a little here. when i lock up on snow or ice the ABS doesn't kick in and a i get a nice long slide. when i try it in uneven tractions situation like slushy snow or standing water it kicks in just fine, awesome stopping. managed to exercise the pump real good in the slush, but it still won't kick in on the snow.

[MT-2500]

Originally Posted by ericn1300

i pulled and cleaned all the connectors and swapped around some relays (not sure which would br the ABS) and took it out for a test drive. things are thawing out a little here. when i lock up on snow or ice the ABS doesn't kick in and a i get a nice long slide. when i try it in uneven tractions situation like slushy snow or standing water it kicks in just fine, awesome stopping. managed to exercise the pump real good in the slush, but it still won't kick in on the snow.

They may be the way they are supposed to work.
Keep in mind the ABS is to keep one or two or 3 wheels from sliding when the other ones are moving /turning.
But if all 4 wheels are sliding it may see a none moving situation and may not kick in.
I always like to try them out on grass or mud.
Or keep one side on dry payment and let the other side have the slick spot.
When the old pedal starts kicking around you know they are working.
Good luck and let us know how it goes.

[Chris Stewart]

I'm not sure, the last time we had enough snow to slide, the ABS worked just fine.

[ericn1300]

they definetly are supposed to work on snow even though after reading this i might actually prefer them not to. from abs-education.org:

In what circumstances might conventional brakes have an advantage over ABS? There are some conditions where stopping distance may be shorter without ABS. For example, in cases where the road is covered with loose gravel or freshly fallen snow, the locked wheels of a non-ABS car build up a wedge of gravel or snow, which can contribute to a shortening of the braking distance.

[MT-2500]

Originally Posted by ericn1300

they definetly are supposed to work on snow even though after reading this i might actually prefer them not to. from abs-education.org:

In what circumstances might conventional brakes have an advantage over ABS? There are some conditions where stopping distance may be shorter without ABS. For example, in cases where the road is covered with loose gravel or freshly fallen snow, the locked wheels of a non-ABS car build up a wedge of gravel or snow, which can contribute to a shortening of the braking distance.

Well there is a lot of pros and cons.
Abs brakes are nice when you need them.
But not a cure to a skid problem.
They are made to keep wheels breaking even.
But if you hit a slick curve at 80 MPH they may not save your life.
But stopping on slick road conditions they are designed to keep 1-2-3 wheels from sliding more than others.
But if no wheels are holding and they all 4 lock up the ABS wheel sensors will see a no car/tuck speed. And may just shut down until one wheel starts rolling.
They only kick in after a certian MPH and will only activate when the wheel speeds is uneven.
From what you have described on yours they may be working as designed.
No codes or ABS light usually means no problem on them.
But if you do not think they are right you need to get them checked on a ABS capable scanner to be sure.
Good Luck
And let us know how it goes.