Problem is the gauge quit working and low fuel light stays on, which means fuel is not transferred from rear tank and you don't have a gauge to tell you when you are out of fuel, even though the back tank is still full. The balance module needs input from both tank gauges to signal fuel transfer relay to turn on transfer pump to move fuel from rear tank to front tank where engine sucks all the fuel from and returns to. This system is obviously only only on trucks with two tanks and maybe only on diesels because gas engines have pressure pumps in the tank(s) to supply fuel injection. There seems to be little understanding of how this works and dozens of variations of tanks, gauges, balance modules etc. There are thousands of pages of problems and discussion of how to trouble shoot and fix this problem on line. Me and a pretty experience HD tech have spent part of 2 weeks researching this problem and are not much smarter than when we started other than thinking we know how it works. We have changed the transfer pump, changed the instrument cluster, checked all the fuses that supply power to the different components (but still don't know where power comes from to supply the gauge), taken both senders out of the tanks to ensure it is not a float hung up(common problem), checked ohms of senders at full and empty(does not seem to be a dead spot anywhere), checked and recorded voltage at all pins in the 20 pin connector at fuel transfer module(don't know what those mean), drove truck to Vancouver and back(2500 km) and had intermittent fuel gauge operation on original cluster(appropriate name for this system!). Does anyone know how to fix this system before I install a Stewart Warner white man fuel gauge and a manual timer for the transfer pump?