use a DMM to test ground?

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kalito

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Joined: January 14, 2004

Posted: March 11, 2004 at 12:18 PM / IP Logged

like the topic saids .... i read in one of the post about using a DMM to test for a good resistance for good ground, i just bought a DMM .. http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5fid=22-810 now i was wondering if some can shool me on how to do it ... ?

or just give me a few pointer on what are the thing i can use i for ...

kgerry

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Posted: March 11, 2004 at 1:17 PM / IP Logged

run an 8 gauge jumper cable from the negative post of the battery and then meter for continuity from this cable to the point at which you ground the amp...should be very low impedence, maybe an ohm or so....anything higher is a bad ground....

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forbidden

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Posted: March 11, 2004 at 1:17 PM / IP Logged

Do a search for this, I have discussed it on similar topics in the last 2 months.

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markcars

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Location: New York, United States

Posted: March 11, 2004 at 2:33 PM / IP Logged

it should be zero and nothing else. if it shows 1 ohm, then your contacts from the meter aren't too clean or good, but really they should be zero. Anything other than zero means it is not ground as you would want it to be.

Usually any non-separated metal part of the car is a good ground.

kalito

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Joined: January 14, 2004

Posted: March 11, 2004 at 2:42 PM / IP Logged

forbidden wrote:

Do a search for this, I have discussed it on similar topics in the last 2 months.

i did search but i didn't get any results back when i look on the topics... and when i look ito the body massega i would get like 60 pages... i so post it so whenever someone need it loke myseft i'll be alot eazier to find ...less time searching+less time meesing+ less time guessing = more time to enjoy... use a DMM to test ground? -- posted image.

use a DMM to test ground? -- posted image.

Teamrf

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Posted: March 11, 2004 at 3:17 PM / IP Logged

Well a good ground usually shows between 0-0.07 in resistance. So if your ground resistance is any higher you need a new ground.

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forbidden

Platinum - Posts: 5,352

Joined: November 01, 2003

Location: Alberta, Canada

Posted: March 11, 2004 at 4:09 PM / IP Logged

Take a length of primary wire for an extension cable as your probe wires are not long enough. Do not touch the bare wires or probes when you check for resistance. Attach the negative lead to one end of the extension wire. Attach the other end of the extension wire to the battery neg. Touch the positive lead to the neg battery. If yuo have a good connection the reading should be zero, if it is not double check the connection at the battery and at the wire to probe.

Find your ground point in the back of the car, take the positive lead and check the reading. If the reading is above .5ohm it is a good idea to find a new ground or ground direct to the battery. If your amp is already installed, disconnect the ground from the amp and check the resistance reading again by attaching the positive probe to the bare part of this wire, again do not touch the wire or probe. Hope this helps you. Let us know what you find and what the vehicle is.

Top Secret, I can tell you but then my wife will kill me.

markcars

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Joined: December 11, 2002

Location: New York, United States

Posted: March 11, 2004 at 4:56 PM / IP Logged

Teamrf wrote:

Well a good ground usually shows between 0-0.07 in resistance. So if your ground resistance is any higher you need a new ground.

where did you come up with that range? 0-0.07

Agreed that if it is higher, a better ground needs to be found but just wondering where the .07 value came from. Just curious.

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use a DMM to test ground?

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