Grounding Issue in 96 Explorer?

How is the battery negative to body ground ?. Normally you have a big wire going between the battery negative and the engine but since it's on rubber mounts it's tied very poorly to the body of the car (potential but poor grounds are shifter cables and emergency brake cables). This is why there is another connection between the battery negative and the body or from the engine to the body. Slowly work away from having both meter leads on the battery and see where the drops are occuring the further you move the one test lead away from the battery.

Jim

I doubt that 25 ohm reading is correct; if it was, nothing electrical would work on the body. Measure voltage from the same two points.. as was pointed out earlier, you shouldn't see more than 0.5 v.

Jim

Otter,

Have you tried yet with the meter having both test leads on the battery and then moving one away from the battery to the next connection ?. Is it possible the meter is defective or set wrong ?.

I would maybe do these steps:

Disconnect the positive terminals off of the battery.

Place both meter leads on battery negative terminal (should read 0 ohms and if not then zero the meter, try a new battery, or write the figure down it is showing but this should only be maybe 1-2 ohms tops as a higher reading would lead me to believe a defective meter and or test probes)

Now leave the one test lead on the battery negative post and take a 15' or so chunk of 16-18 gauge wire and with the other test lead connect this to one end of the wire and connect the other end of the wire to the battery negative terminal. The ohm reading should be the same or just a tad higher. Now with the one end of the wire remove that from the battery and trace down where the battery negative cable connects to the body of the vehicle and connect it there and note the reading. Now remove it from there and try a grounding spot under the dash. Now move it even further away towards where you have the amp and where you want to make a ground connection. At some point the readings will jump to the high reading you had. Between this point and the point before should be the problem and then this can be addressed.

If all else fails, run a ground from the battery to the spot you want to grounfd the amp to. Most vehicles are spot welded together and this should allow a decent electrical path but maybe somethings funky like the metal is poor for conducting or the welds are not enough or improper. 

Using the meter to find where the resistance changes is just like seeing how there are voltage drops through different things like connections, fuses, cabling, and so on. You just have to do it in an organized manner and not in a random fashion.

Jim