Bad ground testing ? - Team Camaro Tech
Electrical & Wiring Troubleshooting electrical.

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post #1 of 3 (permalink) Old Jan 17th, 01, 02:38 AM Thread Starter
Tech Team
Join Date: Sep 1999
Location: NJ
Posts: 78

I have a í67 that Iím having electrical problems with. I think most of my troubles can be traced back to bad/missing grounds. What is the best way to troubleshoot grounds for the entire car?
kgaffney is offline  
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post #2 of 3 (permalink) Old Jan 17th, 01, 08:03 AM
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Join Date: Nov 1998
Location: ohio
Posts: 252

About the best way to start is to use a voltmeter and look for voltage between the various ground points. If you get a voltage reading, for example, between the engine and the frame with engine running, you have a bad ground. Ditto light socket ground to frame with light on. Battery post to frame/engine. ETc. Should get no voltage readings if ground connection is good.
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post #3 of 3 (permalink) Old Jan 18th, 01, 03:04 AM
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Join Date: May 2000
Location: Warren, MI
Posts: 31

The best and most correct/accurate way to test grounds is voltage drop testing. Do not try to resistance check a ground. The number one reason for this is that when checking resistance, you're checking a "dead" circuit with the power off (no current flow). You could have a circuit with several broken strands of wire but still have good continuity/low resistance.

Try this.....With the circuit powered up, take your DVOM/Voltmeter and check the voltage between the ground terminal of the device in question and the negative battery cable. The meter will give you a reading of the voltage being consumed in the ground circuit. In other words, how much voltage does it take for the ground circuit to make the path from the device's ground circuit to the negative battery post. So, this being said, a device with a 14v power source and ground with 4 volts of drop, means the device being powered is only operating at 10v. This can cause dim lights, lazy wipers, poor audi reception/performance, poor/weak spark, etc....

In a perfect world, a good ground would have a voltage drop of 0v. However, you will usually observe .1-.6V. Usually if you observe a voltage drop of greater than .7-1.0 volts on a ground, repair the ground.
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