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Bombardier F-N-R Sauer Danfoss problems

B

brushcutter

New member
Hello, I have a Bombardier GT500HY (Go-tract) that was purpose built as a brush cutter back in 1999. I run a Fecon forestry mower on the front of it on loader arms. I know I am a bit of an oddball on this forum but this machine is just a beefed up snow cat. I have been having a problem with one the joy sticks that control the tracks (F-N-R) and the Sauer-Danfoss micro controller (blue box). The digital display on the box will suddenly show "GT500 unknow" and the machine will not move. This happend several weeks ago and I sent the controller back to Bombardier (Prinnoth) they reprogramed it and it worked fine for a few days then it did the same. Does anyone know what could cause the micro controller to suddenly loose its program. I have been having some issues with one of the F-N-R sticks that will sometimes cause the controller to show a PF2 code on the screen and the machine stops and I restart and continue working. Could the problem F-N-R cause the controller to loose its program? I have been havinig this F-N-R problem for over a year and has not caused any problems in the past. My voltage guage seems to be reading low when there is an electrical load. I will check the system today(possible bad alternator). Could low voltage cause this? Anyone with ideas? Thanks in advance for any input.
 
I don't know anything about SnoCats, but I do know that electronics do not like to be underpowered. Low voltage could, indeed, be your problem. Many electronic componants shut themselves down under low voltage conditions as a fail safe against completely toasting them. This might be where you're losing your program. First though, check alternator belt(s) for condition and proper adjustment. If you're running electrical equipment, such as the fan for AC or heat, there's a good load. Any lights will load it further.
A simple volt meter will tell you a lot. Check battery voltages with the engine not running. Check again with engine running. You should be getting something above 13V on each battery with it running. 11-12.5 or so not running is good.
On a machine like that, vibrations kill batteries. If they're 2 yrs old or more, they're probably good candidates for replacement.
 
Thanks for your input. I will check the voltage like you said today and I'll let you know what I find. On the gauge in the cab it will sometimes drop down to 10v and quickly come back up to about 12. It seems like this could be the problem. Thanks
 
One thing, since you've got such a drastic voltage drop and rise, is that a connection in the charging circuit could be bad. Check 'em all, even if they don't show signs of corrosion. That film that develops on connections is enough to screw electronics up. Many a module in automotive use is toast because it's underpowered, ever so slightly, due to that film.
 
The voltage at the batteries is 12.5 not running and the voltage while running is 14.0, but I did notice a very loose connection on one of the batteries. There is one battery that connects from the positive directly to the starter and then a jumper from that positive to the next battery positive(the one that was loose) and that same positive has a lead that may feed the micro controller. I will check out a print on the machine. Thanks
 
Nearly every time I've had a weird electrical problem it has been a bad or poor ground connection.
 
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