well with a fluke meter on the battery you should see a drop say like example 12.5 volts to 11 or 10.5 inload (cranking) also you can see a possible neg. voltage drop by touching neg.lead to motor instead of battery and pos.lead to battery pos. and read possible neg . voltage drop (loss), then get under there and touch positive lead to battery pos terminal a starter and neg lead on starter housing and read voltage drop in start up (cranking) This is a way to see if starter is getting full battery pos and neg , then to go further you can ohm out the battery pos cable cable from starter to battery pos terminal should be 0.0 to .2 hope this helps it will also give you some insite yo how the system works