auto earth test using multimeter, any ideas?

[vijay]

ok this isn't strictly diy in the home , but in the car. I've wired up an amplifier in the car however I'm not sure of the quality of the negative/earth that i have connected to the car body. Using a multimeter can i check the quality of my earth against other earthing points to get a reading and compare? If so how do i do this?

 

[breezer]

Yes you can, but assuming yuor "earth is connected ok, it would be a waste of time.

There are several things you should make sure you have done.

The vehicle and your device are both negative earth

Where you are connecting to is clean and paint/ grease free (so you can see bare metal)

The wire you are connecting with is the right one.

You are using a crimp terminal on the wire you are connecting with.

You can just use the stripped wire, but if so pout a metal washer on the screw so that when you tighten it up it only compreses the stripped wire to make good contact with the metal

You are connecting to a part of the cars body work, nopt on a shelf.

so long as you check the above you can take it as read you have a negative.

If you still want to test it set your meter for volts dc, connect the red lead to the + of the car battery, and touch the black lead to your intended earth point, you will get 11- 13 volts