Mar 18, 2016 (4 years ago)
Clean each end of the starter heavy cable,
REALLY clean so bare metal shows through.
And the same with the main engine earth/ground cable,
And where this cable bolts to the engine and chassis.
And I really mean clean,
I would use as a minimum a rotary wire brush.
Reason for all this is you have a high resistance in the circuit somewhere.
It may even be internal to the cable themselves.
But where the cable connect is a good place to start.
Or you could check all the cables/connections for high resistance with a DVM.