F150 Brake Problem
11-19-2011, 10:55 AM
#11
Junior Member
Join Date: Nov 2011
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
ABS Valve in 97 F150 4 wheel drive
The brake light was staying on. The dealer (I was there because of gas tank strap recall) charged me $96 to "analyze" my problem. I had a bad back brake which I had replaced at my local garage. 
The dealer also said i need a "ABS VALVE" for rear brakes at a cost of $300. I went to the junk yard and they don't have one right now. My garage doesn't know anything about them, and they are a very good garage. It drives fine without it. Can I just skip replacing it? I only use the truck around my farm, and I go slow.
Glad I found this forum! Yay! Haven't been on a "forum" since I had my F650GS BMW thumper! That was a fun forum. I hope to enjoy this one as much!
The dealer also said i need a "ABS VALVE" for rear brakes at a cost of $300. I went to the junk yard and they don't have one right now. My garage doesn't know anything about them, and they are a very good garage. It drives fine without it. Can I just skip replacing it? I only use the truck around my farm, and I go slow.Glad I found this forum! Yay! Haven't been on a "forum" since I had my F650GS BMW thumper! That was a fun forum. I hope to enjoy this one as much!
04-08-2015, 11:58 AM
#12
Junior Member
Join Date: Apr 2015
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
More often than not if you have not been working on your brakes to the point to allowed air into the brake lines, not leaking brake fluid or not having to add fluid and gradually end up with a mushy pedal it is the master cylinder leaking past internal seals.
If you have replace the mater cylinder with one of the Pep-boys or Auto zone or that type of parts store and it has a warrantee I would return it for another one and try it again. It does happen to get one out of the box with a problem. With the reinstall and bleeding the brakes and still have a mushy pedal it could be the ABS modulator. The modulator will have problems usually due to debris that end up in the system over the years. If this is the case the only fix it to replace it. If when you did replaced the pads you may have ended up forcing the calipers open to create enough clearance for the new pads to go over the disk. It is very important more so with ABS to open the bleed valve at the wheel you are working on before forcing the calipers open. This will allow the old fluid to bleed out at the wheel instead of forcing it back into the system. If this was not done back flow debris can make it back into the modulator which means a replacement of the modulator. I could not find an after marked one ended up going to the dealer and it was over $400. You might be able to pick one up at a junk yard however you are taking a chance that it is no good. Bleeding the modulator correctly takes a switch assembly that allows you to open and close the valves. I can not remember if I ever found the switch assembly to buy or if the cost turned me off. There is a way to bleed the modulator with out the switch however not very handy. After bleeding the brakes as normal making sure the reservoir is full find you a road where you can get up to speed no more the 35mph should work and slam hard on the brake making the ABS work as it would in a panic stop and it will get the air out of a newly installed modulator. You will have to bleed what air came out of the modulator which will move into the system by bleeding the brakes as normal again. At this time the brakes might be working somewhat but pulling strong to left or right meaning you need to do a few more panic stops. I ended up doing two sets of panic stops and break bleeds. All worked well.
If you have replace the mater cylinder with one of the Pep-boys or Auto zone or that type of parts store and it has a warrantee I would return it for another one and try it again. It does happen to get one out of the box with a problem. With the reinstall and bleeding the brakes and still have a mushy pedal it could be the ABS modulator. The modulator will have problems usually due to debris that end up in the system over the years. If this is the case the only fix it to replace it. If when you did replaced the pads you may have ended up forcing the calipers open to create enough clearance for the new pads to go over the disk. It is very important more so with ABS to open the bleed valve at the wheel you are working on before forcing the calipers open. This will allow the old fluid to bleed out at the wheel instead of forcing it back into the system. If this was not done back flow debris can make it back into the modulator which means a replacement of the modulator. I could not find an after marked one ended up going to the dealer and it was over $400. You might be able to pick one up at a junk yard however you are taking a chance that it is no good. Bleeding the modulator correctly takes a switch assembly that allows you to open and close the valves. I can not remember if I ever found the switch assembly to buy or if the cost turned me off. There is a way to bleed the modulator with out the switch however not very handy. After bleeding the brakes as normal making sure the reservoir is full find you a road where you can get up to speed no more the 35mph should work and slam hard on the brake making the ABS work as it would in a panic stop and it will get the air out of a newly installed modulator. You will have to bleed what air came out of the modulator which will move into the system by bleeding the brakes as normal again. At this time the brakes might be working somewhat but pulling strong to left or right meaning you need to do a few more panic stops. I ended up doing two sets of panic stops and break bleeds. All worked well.
The pedal pushes right past what should seemingly be the booster length, down to the manual pedal, and it takes quit a bit of force to make the truck come to a stop.
I don't know what else to do, cause I don't beleive the modulator would be "bad" but if there is air in it I can't imagine that's a good thing.
04-16-2015, 01:20 AM
#13
Junior Member
Join Date: Aug 2007
Posts: 3
Likes: 0
Received 0 Likes
on
0 Posts
This has been helpful, however the problem I'm having with the mushy pedal won't give me enough brake power to make the ABS modulator even work.
The pedal pushes right past what should seemingly be the booster length, down to the manual pedal, and it takes quit a bit of force to make the truck come to a stop.
I don't know what else to do, cause I don't beleive the modulator would be "bad" but if there is air in it I can't imagine that's a good thing.
The pedal pushes right past what should seemingly be the booster length, down to the manual pedal, and it takes quit a bit of force to make the truck come to a stop.
I don't know what else to do, cause I don't beleive the modulator would be "bad" but if there is air in it I can't imagine that's a good thing.
I am not an expert on this just a back yard mechanic. Not sure what tell you. I am still driving the truck and no problems with the brakes after the posted fix.
The break system in my 96 f150 4x4 is a fairly simple system. Hydraulics just needs a clean sealed system of oil without any air bubbles to work.
If you see no leaks found at each wheel slave cylinders, no line leaks, no leaks at the master cylinder or ABS modulator all that is left is trapped air, goofed up modulator, or internal by pass of oil in the master cylinder.
Until I got mine fixed my brakes did work however I did have to stand on them almost to the floor to get them to stop the truck. I did not allow my wife to drive it until I got it fixed.
The modulators are for the most part a non-issue and less likely to be an issue. Air in the lines does not just happen. It happens if you run the reservoir low and air enter from a low level in the reservoir while using the brakes. Also can enter after opening the brake lines and not bleeding them or bleeding incorrectly.
If no leaks and the reservoir always at the correct level and the system were not opened it would prompt me to lean toward the master cylinder. A few times I have brought home from the auto zone or pep-boys type parts house a so-called remanufacture master cylinder and it had an internal issue right out of the box. Had the same thing happen with a few alternators not working correctly out of the box.
I doubt it is the power assist system what keeps the pedal from traveling past normal is the hydraulic resistance from a sealed system. Oil can not be compressed however air can. The mushy feel comes from trapped air or a bad master cylinder not sealing internally.