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spankyjr1, Journeyman
Category: Medium and Heavy Trucks
Satisfied Customers: 2563
Experience:  I worked on all types of equipment semis,forklifts,farm,ect.
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2001 peterbilt. When stepping on brake, it feels like no brake

Customer Question

2001 peterbilt. When stepping on brake, it feels like no brake then all of a sudden you got brakes. I've changed tractor protection valve and foot pedal valve.
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Customer: replied 1 year ago.
Kinda feels like abs is kicking in but on dry pavement. Have no air leaks.
Expert:  spankyjr1 replied 1 year ago.
Hi and welcome my name is ***** ***** any lights coming on while braking like abs?
Expert:  spankyjr1 replied 1 year ago.
Try pulling abs fuse, that should revert truck back to regular braking and turn abs light onDo you know what brand abs you have like Bendix?
Customer: replied 1 year ago.
No, I just had that system checked out, it suppose to be ok
Expert:  spankyjr1 replied 1 year ago.
Have you checked brake adjustment and do you have 4 maxi chambers?
Customer: replied 1 year ago.
The light comes on at start up then goes off like suppose to
Customer: replied 1 year ago.
They r in adjustment . Only 2 maxi brakes on front rear axle
Expert:  spankyjr1 replied 1 year ago.
pull abs fuse and test drive this would eliminate a abs valve or other abs issue we need to know which way to go.
Customer: replied 1 year ago.
Had abs checked out , front right sensor was bad, replaced it and 392$ later it suppose to be right. Light wasn't coming on , they found wire broke going to ecu nd fixed it and replaced sensor
Expert:  spankyjr1 replied 1 year ago.
I'm not trying to be difficult but when I check brake systems I eliminate the abs so truck goes back to regular braking even if abs checks okayIf you do not want to try this I will opt out and put back on open board for other experts to review and assit.Let me know
Expert:  spankyjr1 replied 1 year ago.
The question will remain open
Customer: replied 1 year ago.
So pull fuse and test drive it
Expert:  spankyjr1 replied 1 year ago.
Yes please
Expert:  spankyjr1 replied 1 year ago.
I will be around in/out through the day so just reply back after test
Customer: replied 1 year ago.
Pulled fuse ,5th one down on right side of panel marked abs/aux. Problem still happens driving highway speed then pulling off into rest area.
With fuse out the abs check light still came on. Thought that was funny but that's the only fuse marked abs.
Expert:  spankyjr1 replied 1 year ago.
Thanks for additional info.The ABS light will still come on since ecm sees no abs signal.The next thing you would need to do is check air pressure in/out of the treadle valve (foot brake) the supply air pressure may be low from kinked line ,bad check valve, ect.The treadle valve ports are marked in/out you will have to tee into lines and check pressures.You already changed treadle valve and have same issue so I think its low air supply.Another thing you may want to do is check air tank pressures on both sides of each tank,,,some air tanks look like they are one tank but are actually divided into two tanks with a internal check valve,if check valve is bad tanks won't equalize. You may also have check valves on outside of tanks so I would check them first before teeing into treadle valve checking pressures. Just remove check valve and see if the guts came apart.
Expert:  spankyjr1 replied 1 year ago.
Let me know if you need anything else.Thanks
Customer: replied 1 year ago.
I won't be back on shop til next Friday. On road now. What about valve that splits air to rear brakes. Looks like it sits on top of two other valves .
All lines are orange or green. Is one color supply other parking?
Expert:  spankyjr1 replied 1 year ago.
Yes, one is for service and one for park brake.You still need to start with supply air the other valves will not work correctly if the supply air is not their its all related.

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