On modern motors electrical problems can be a nightmare,but when you have the correct computer you can activate your gauges/lights/horn/wipers etc and this checks out your ecu and the wiring to your units and narrows down the search,as for your guage on some models you can ask for empty/half/full readings and will narrow down your searches,possible cause-tank unit but that is just a guess and just guessing can work out to be very expensive.
cdc, October 2013
