I have a Bobcat 864 track loader, and immediately after firing up the computers sounds 3 beeps, and error codes 08-21 and 12-21 appear (temp sensor high range and PWM high range) I have removed the temp sensor and checked resistance, and it seems okay (~1060). when I place back in the machine The error code still shows even when the sensor lead is disconnected. I have checked wiring for the sensor and the right control arm and no indication of grounding Any ideas on where to go from here would be appreciated
I don't have a manual for the 864 so I don't know what the ohm range is for the engine coolant temp sensor is, but simply replacing it would help eliminate that being the problem, I doubt the sensor would be terribly expensive. But that code 12-21 is a problem. That code typically indicates a faulty thumb switch for the aux control on the right stick. No way I know to verify that thumb switch is faulty as it's a Hall Effect switch and I'm not aware of a way to test a Hall Effect circuit. Don't mean it can't be done, just don't know how myself. Problem is, if that switch is bad, you can't simply replace the switch as it's a unit of the of the right drive stick handle, have to replace the entire drive stick handle and the only place you can get that is Bobcat.
Thanks for the quick response. Shouldn’t the 08-21 fault code go away if the sensor is unplugged? looking forward to pricing the right control switch!
Not necessarily. That's where this gets weird. The main controller is looking for correct inputs from sensors. If the sensor is faulty causing an "out of range" input, just because you disconnect it doesn't necessarily mean you "re-set" that input, it's going by the last input. Now if it had a code for "open circuit", that would indicate the sensor disconnected, but there's no code for that so it's not looking at that. Just saying the temp sensor wouldn't be a problem until you got code 08-11 temp extremely high or code 08-15 coolant temp in shutdown. But that code 12-21 will affect machine operation until it's corrected. Bottom line, only way to verify sensor is not bad is replace sensor. If you still get the code, not much else you can do to troubleshoot, you'd need a Bobcat tech. And likewise, not much you can do to troubleshoot 12-21 aside from replace the knob assembly on the right stick, that would cost you a bit more coin with no guarantee that it fixes the problem, back to needing a Bobcat tech to verify as only a Bobcat tech can plug into the machine and access the main controller and various components with their computer.
That makes perfect sense. I’ll get the temp sensor and give this a try. I see that the right stick handle assembly is $350. I can’t get a Whitestar technician to do anything for $350, so I will try that too. Thank you for your help.
Okay, thought I'd give a quick update and also see if anyone out there has any additional suggestions. When I disassembled the stick handle assembly the contact pins were severely corroded-- to the extent that one or two of them were missing altogether. I replaced the hydraulic temperature sensor and the right stick handle assembly and the 12-21 fault code no longer displays. I also replaced the hydraulic temperature sensor at the base of the filter assembly, but the 08-21 code still appears. Any ideas?