[mwebb]

OHM Meters are right next to useless when working on cars
the ECM does NOT see resistance .
the ECM Does see voltage and in a loaded / working circuit Voltage drop is one of the primary causes of broken cars , you will NEVER find a voltage drop with an OHM meter.

OHM meters can not load circuits and can not test loaded circuits.

ground circuits should all be the same as battery negative
so
negative test lead on battery negative , positive test lead on suspected ground , engine at idle with heater blower maxed and High beams on

voltage on the ground circuit with respect to battery negative can not be above
50 millivolts or .050 volts for "smart" computer related circuits
or 200mv or .2 volts for "dumb" circuits that are not computer related

lower is better .

0 volts is the optimum and sought after voltage drop value .
in a LOADED circuit
with respect to battery negative , when testing grounds

and when testing supply , the same values apply , with respect to battery positive OR alternator positive which should be 0 volts different from each other in a loaded circuit in a perfect world .

you can make redundant grounds or repair damaged corroded connections as needed to get voltage drop values within spec
no "kit" required .