Brake light comes on....'96 K1500 w/ ABS

[billy bee]

After a panic ABS stop (while towing) my "Brake" light came on and the pedal has been spongy, with long travel. Pump the brakes, and the pedal comes up and the light goes off.

I bled the brakes and everything seemed fine while bleeding, but it did not solve the problem. I suspected the M/C was going. So, I replaced the master and bench bled as required.

When mounting the M/C, some of the fluid drained out of the front hole in the M/C. I suspect it lost it's prime, essentially. I have tried to bleed the brakes several times and keep getting air out of the rears.

Before I bench bleed it again and start all over, am I missing anything? What else would cause the "Brake" light to come on?

Thanks in advance,
Bill

 

[kennythewelder]

I suppect you have trapped air in the system. A pressure bleed, and then the ABD needs to be cycled again. Then another bleed should do the trick. To cycle the ABS valve, the easy way, drive on a gravel road, and slam on the breaks, making the ABS engage. This will cycle the ABS valve and release any trapped air that may be behind it. You may need to repete a few times to get the air out from in back of the valve. Repete bleed, and this should work. Last time I did a MC swap, I bench bleed the new MC, then I bleed each wheel 6 times, then I repeted this again on each wheel. So at the end of it all, I had d bleed each wheel 12 times. My wife said Her leg was sore for 2 days. She was pumping the brake peddle. It made a big difference in my brake performance. This is when I did the GMT 800 MC swap on my 97. Some here say its not a good swap, but it works grate for me.

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[kennythewelder]

Oh and you can also bleed the MC on the truck just like you do the wheel cylinders. By cracking open the lines while someone holds pressure on the brake peddle after pumping it a few times, but it does make a mess, and you will need to bleed the wheels after.

 

[94burbk1500]

Probably air in the ABS module. You can try

I suppect you have trapped air in the system. A pressure bleed, and then the ABD needs to be cycled again. Then another bleed should do the trick. To cycle the ABS valve, the easy way, drive on a gravel road, and slam on the breaks, making the ABS engage. This will cycle the ABS valve and release any trapped air that may be behind it. You may need to repete a few times to get the air out from in back of the valve. Repete bleed, and this should work. Last time I did a MC swap, I bench bleed the new MC, then I bleed each wheel 6 times, then I repeted this again on each wheel. So at the end of it all, I had d bleed each wheel 12 times. My wife said Her leg was sore for 2 days. She was pumping the brake peddle. It made a big difference in my brake performance. This is when I did the GMT 800 MC swap on my 97. Some here say its not a good swap, but it works grate for me.

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I was just typing up basically the same thing you said! Give this a try Billy and if it doesn't work, you might have to have a shop do a true ABS bleed with their scan tool.

 

[billy bee]

Well, I think I have a complication: after my 6th bleed and after cycling the ABS twice as you guys suggested, I heard a thunk and then a jingling sound from the right rear. I think the rear brake hardware is now rattling around in the drum. I am not in a position to jack the truck and remove the wheel; so, I'm gonna park it for now and return to it in a few weeks when I have some more time.

Thanks for your help, guys. I'll circle back when I have had more time (and patience) to investigate further.

--bb

 

[sixteenacrewood]

I would get a cheap vacuum pump, I got one just for bleeding the brakes, you don't need any one to help you and changing the brake fluid takes a half hour

 

[billy bee]

Thanks for all of your replies. I do have a mighty vac. It does work well. I just don't have it at our vacation home where the brakes took a dump.

I took the truck to a shop where they did a pressure bleed and cycled the ABS. Problem solved.

bb