Alright so my 2009 Sportster (Nightster) has two grounds, a engine chassis ground which is the cable from the negative battery terminal to the engine, and a powertrain ground which is where all the components (headlamp, controls, fuel pump etc) ground out to.
When I test the engine chassis ground point (red lead to pos battery) it matches the voltage in the battery ~12.7, but when I test the powertrain ground point it drops to ~10v. Also If I measure any of the component ground connects (headlamp, controls, tail lights, fuel pump etc) it matches 10v. I'm assuming there is a fault somewhere in the powertrain component ground wiring, but not sure exactly how to search for it.
To add if I unbolt the powertrain ground from the engine block, and test the wire I get 1.544 volts. Does that mean it's grounding to the frame some how?
Not sure if this is relevant, but with the powertrain ground rebolted to the engine, if I touch the engine block or engine fins, I don't get any volt measurements, but if I touch the top of the engine, the chrome head above the engine fins, or any bolts, I get 10v readings...
Any idea how to resolve this?
