Hello I have a bobcat 763 and the parking brake won't release. I have only one voltage on the pull relay. If I jump it the solenoid works. No power coming from the computer side. I have around 6 volts on the hold coil pin, is this enough voltage for the hold pin side. I checked the wire coming from the computer to the relay it has a good ohm reading. Also I have 12 volts at the parking brake switch coming in and going out to the two wires. The machine will show sometimes a code for traction lock, saying a short, damage harness or computer, low to no voltage at solenoid. I bought a new solenoid also same thing. Sometimes the parking brake light flashes 3 times before pausing.I think it might be the computer. I don't have a wiring diagram to trace the harness to verify the harness has no problems. But sometimes the screen shows a code for another hydraulic fault then it disappears and the traction lock shows up.
check the engine speed sensor. the controller needs to see a signal from the speed sensor, (telling it the engine is running) before the brake will unlock.
Yes I checked that also it's a smooth engine RPM read out.
checked it where? via the dash readout? i was always told, but it was never confirmed by bobcat, that the dash readout gets it's signal from another source, (possibly the alternator), if the engine speed sensor is ot operating correctly the brake will not unlock
I'll have to check that. I know on the s130 if there was no signal or it bounced around it wouldn't unlock. Thanks guys.
Ok I checked unplugging the RPM sensor the signal cuts out. Plug it back in and the signal comes back with a smooth RPM reading.
my suggestion would be to remove the speed sensor, wipe the tip off, reinstall it. turn it in BY HAND until it bottoms out, back it off 1 wrench flat, and snug up the lock nut. if that fails, swap the relay with a good relay, ie: start relay, check the brake fuse and relay socket for corrosion, make sure you have power on both sides of the fuse when the key is on. you didnt mention if anything else is not working, so i'm assuming the switch power fuse and relay are good.
Relay only has one power. If I jump it the solenoid works. Theres no power from the computer side to the relay to activate it.
I have a new power probe I'm waiting to test now.
the brake works in 2 steps, one coil pulls the stem up, and holds for approx 3-5 seconds, ( then drops the stem) "pull" power comes from the brake fuse and relay, the 2nd coil holds the stem up, and gets it's power directly from the controller.. just as a thought, start the engine, leave the seat bar UP, and hit the traction lock override and see if the brake releases. if you have the park brake switch on the floor of the cab between your feet, disconnect it from the main harness, and see if the brake releases. occasionally the switch stops working or is damaged.
Crewchief888 thanks for the help I think I got it. Just need to reinstall the mechanical part of it and check again.