753 Brakes wont unlock

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Crashly

Member
Joined
Feb 23, 2006
Messages
17
My 753 has been sitting a few months and It will start and run just fine, the bucket controls work the aux hydraulics work but the machine will only roll back and foward a few incghes before the brake engage. I flicked the parking brake a number of times but this did nothing. I checked all of the BICS lights and they are all green when I am sitting down with the seat bar lowered. I can not get the traction lock overide switch to activate either. It usually makes a clunk sound when the button is pressed, but now nothing. Anybody have any ideas?
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
check your fuses, there is one for the brake, either power is not going to the pb soliniod or the soliniod is burnt out.
It is located on top center of the chain case under the cab/seat. round thing with 3 bigger wires.
remove the 2 1/4” bolts that hold it down, slide it up and off.
in the center of it is a rod @ 5/8 diameter, pull it up a 1 1/2” or so, put a hose clamp around it to hold it up and drive off.
Ken
 

Crashly

Member
Joined
Feb 23, 2006
Messages
17
check your fuses, there is one for the brake, either power is not going to the pb soliniod or the soliniod is burnt out.
It is located on top center of the chain case under the cab/seat. round thing with 3 bigger wires.
remove the 2 1/4” bolts that hold it down, slide it up and off.
in the center of it is a rod @ 5/8 diameter, pull it up a 1 1/2” or so, put a hose clamp around it to hold it up and drive off.
Ken
Thanks Ken, I wetn and found the lock cylinoid. I will unplug it tommorow, remove it and clean it up and see what is going on with it. I park the bobcat on hills all of the time while it is running so the brake needs to be working and trustworthy. Do you know where the fuses are located? How do I test the cylonoid. I would think that the traction lock and parking brake work in conjuction with each other via a cylinoid???
 

skidsteer.ca

Well-known member
Joined
Jan 20, 2006
Messages
3,853
Thanks Ken, I wetn and found the lock cylinoid. I will unplug it tommorow, remove it and clean it up and see what is going on with it. I park the bobcat on hills all of the time while it is running so the brake needs to be working and trustworthy. Do you know where the fuses are located? How do I test the cylonoid. I would think that the traction lock and parking brake work in conjuction with each other via a cylinoid???
track lock and park brake are the same.
of the 3 wires one is ground,
one is the hold wire, it needs + power to hold the brake released.
the 3rd wire is + boost power and gives the solinoid a momentary shot of current to drive the solinoid from brake on to brake released.
once the brake is released the current from the hold wires is enough to keep it released, but not so much the solinoid will overheat.
the fuses on c and f series are under 2 square covers in the engine bay.. 1/2 way up on right,
the fuse labeled “brake” is for the boost wire
Ken
 

Crashly

Member
Joined
Feb 23, 2006
Messages
17
track lock and park brake are the same.
of the 3 wires one is ground,
one is the hold wire, it needs + power to hold the brake released.
the 3rd wire is + boost power and gives the solinoid a momentary shot of current to drive the solinoid from brake on to brake released.
once the brake is released the current from the hold wires is enough to keep it released, but not so much the solinoid will overheat.
the fuses on c and f series are under 2 square covers in the engine bay.. 1/2 way up on right,
the fuse labeled “brake” is for the boost wire
Ken
Thanks, I appreciate the help
 
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