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Multimeter shows 1.5 minimum?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=77371
Printed Date: May 15, 2024 at 6:35 PM


Topic: Multimeter shows 1.5 minimum?

Posted By: dkeshish
Subject: Multimeter shows 1.5 minimum?
Date Posted: May 06, 2006 at 5:25 PM

Hi guys if you are familiar with my posts I have this huge grounding issue in my 2006 chrysler 300. for some apparent reason I cant get a good ground. I DONT KNOW WHY! if you know this vehicle the battery is in the trunk. I read somewhere that its not good to connect the amps ground to the bettery so I connected it to the wire that is from the battery to the car. So I check with my DMM from the car battery to that bolt and its at 1.5 I check elsewhere and there is nothing less than that. WHAT THE HECK? I have 2 amps and they arent connected. Please help.  am i checking the ground incorrectly?

I turn the multimeter on switch it to 200, not 2k, not 20k not 200k and connect both the + and - wires to check how calibrated the meter is. it reads .3

after that I connect the - lead to the - of the battery and the red goes anywhere i want to mount the ground....




Replies:

Posted By: Aruman
Date Posted: May 06, 2006 at 7:06 PM
did you try different DMM?

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Shaking The Neighborhood




Posted By: dkeshish
Date Posted: May 07, 2006 at 1:45 AM
Yes I bought a brand new one.




Posted By: zhalverson
Date Posted: May 07, 2006 at 1:56 AM
I'm assuming you have read the grounding sticky.  Sometimes the resistance of the actual vehicle can be high.  From what I understand the actual ground in a vehicle is the alternator body.  Since in your car the battery is grounded in the back the resistance between there and the alternator through the frame etc. can be high due to welds and other imperfections.  I think an option would be to run a power wire from your amps' grounding point or battery (whatever's easier) and connect that to the chassis where the alternator is grounded.  Someone correct me if I'm wrong.




Posted By: geepherder
Date Posted: May 07, 2006 at 8:47 AM
There's nothing wrong with grounding to the battery if it's close.  I've done that on occasion.  Usually amps go in the back and since the battery is usually up front it makes more sense to ground to the frame/body.  Otherwise you'd have to long ground wire to run, with possibly slightly more of a voltage drop than just grounding to the vehicle chassis.

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My ex once told me I have a perfect face for radio.




Posted By: sparkie
Date Posted: May 07, 2006 at 11:34 AM
Are you checking the ground with the meter set on Ohms? This is not how to check the wire unless the entire circuit is dead. If there is any power to the circuit, you will get a wrong reading. To check for a good ground for your amps, set your meter to a DC voltage scale. Put one probe on the ground connection at one amp and the other probe to a known good ground. Scrape away the paint of the body next to where you intend to ground the amp. If you get a reading of 0.2 volts or less, then you have a good ground.

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sparky




Posted By: dkeshish
Date Posted: May 07, 2006 at 6:34 PM
Sparkie do I disconnect the amp? both power and ground?




Posted By: geepherder
Date Posted: May 09, 2006 at 6:03 AM
Do not disconnect the amp to perform this test.  Sparkie is correct- the voltage drop test is a better test to perform- it can identify weak grounds when under load.

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My ex once told me I have a perfect face for radio.





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