763 Brakes locking up

[Ralph123]

OK, confirmed my Bobcat is a G series. Serial number is 512261407. It has no Seat Sensor. When the glow plugs don't go on there is no error code but it is really a non issue, I just turn the key off and on and they work. The big problem is every once in a while the brakes lock up unexpectedly. You have to hit the Green operator button again and everything is a go. Does it more when it is cold. Kinda dangerous so would like to get it fixed.

 

[walio123]

The reasons for this may be three. Bad or grimy seat bar sensor , bad controller or weak brake solenoid . Next time when this happens, see what LEDs shine.When the parking brake turns by itself , without pressing the green button, can you move the bucket and arms?

 

[Ralph123]

The reasons for this may be three. Bad or grimy seat bar sensor , bad controller or weak brake solenoid . Next time when this happens, see what LEDs shine.When the parking brake turns by itself , without pressing the green button, can you move the bucket and arms?

No everything locks up until you push the green go button.

 

[walio123]

No everything locks up until you push the green go button.

Then reason is a sensor or controller.More likely a sensor. It can be checked with tester. You can only remove the sensor and clean carefully because it have plastic components, careful not to break them. More easily you can remove Seat bar and then take off the sensor.Then remove the keyed plastic bushing, magnetic bushing an sensor bracket. Check for wear.Clean with alcohol and assmble it. Controller can be checked only by bobcat dealer with special softuare.You can not ablle to do this. So try to clean sensor.By the way if the brake is activated when the machine shakes, you may have a weak spring on Seat bar.

 

[Bobcatdan]

Then reason is a sensor or controller.More likely a sensor. It can be checked with tester. You can only remove the sensor and clean carefully because it have plastic components, careful not to break them. More easily you can remove Seat bar and then take off the sensor.Then remove the keyed plastic bushing, magnetic bushing an sensor bracket. Check for wear.Clean with alcohol and assmble it. Controller can be checked only by bobcat dealer with special softuare.You can not ablle to do this. So try to clean sensor.By the way if the brake is activated when the machine shakes, you may have a weak spring on Seat bar.

Did all your problems start when you messed with your battery?

 

[Ralph123]

Did all your problems start when you messed with your battery?

No, It has done it before. Sometimes more often than others. Sometimes you have to reset it a few times before it will even get going. Tried it today in the cold and everything worked OK.

 

[Bobcatdan]

No, It has done it before. Sometimes more often than others. Sometimes you have to reset it a few times before it will even get going. Tried it today in the cold and everything worked OK.

What is battery voltage when running? If the alternator is going over 15 volts, the controller doesn't like this and will start shutting down, doing funny things. Also I wonder about your rpm signal. If the controller doesn't see rpm, it will lock everything because it doesn't think it's running. Dead giveaway is if the glow plug counter is going while it is running.