Checking For A Short To Ground

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With a DVOM

  Remove the power feed (i.e. fuse, control module) from the suspect circuit. Disconnect the load. Set the dial of the DVOM (Digital Volt Meter) to the ohms position. Connect one lead of the meter to one end of the circuit to be tested. Connect the other lead of the meter to a good ground.
 
  If the DMM does NOT display infinite resistance (OL), there is a short to ground in the circuit. Any relatively low resistance reading on the meter is a sign of continuity to ground and a short circuit.
 
  For instance- .2 ohms is a direct short, 10 ohms is also a short, 2,000 ohms is still a short but not a direct one. There may only be a few strands of wire touching ground in this instance. This may not blow a fuse, but with a vibration, it could.

With a Test Lamp

  Remove the power feed (i.e. fuse, control module) from the suspect circuit. Disconnect the load and connect one lead of the test lamp to battery positive voltage.
 
  Connect the other lead of the test lamp to one end of the circuit to be tested. If the test lamp illuminates, there is a short to ground in the circuit because the test light is now feeding power to the circuit and since it is shorted, the circuit is complete and lights up the test light.


 

Hi In the Dodge Ram service repair manual: for a short to ground test the engineer's flow chart says; IF THE RESISTANCE IS BELOW 5 OHMS OR BELOW 100 OHMS ETC. I don't understand that because I learned that a short to ground test should read OLM ohms. Is that correct? Thank you, Frank
 Yes, a short to ground SHOULD test OL on your meter if the circuit is NOT shorted. OL means open, open circuit, infinite ohms, no resistance, no continuity. In a short to ground test OL means there is no short. Any ohms reading would indicate some resistance, so some continuity. But, technically if testing for a short to ground and you get a reading of, say, 20 ohms, that should be too high and can be considered not enough continuity to cause a problem in a 12 volt system because a continuity test of any wire should be less than than .2 - .5 ohms. That may have been true years ago on an older vehicle, but todays computer controls are much more sensitive to resistance.

Thanks for the reply but it doesn't really answer my question, I already read that part about the short to ground and I understand that. I just would like some help with the flow-chart where it says IF THE RESISTANCE IS BELOW 5 OHMS OR 100 OHMS. If a reading on the meter means that a short to ground exist what is meant by IF THE RESISTANCE IS BELOW 5 OHMS ETC It is confusing to me. Thanks Frank.
 Can you send me a pic of the flow chart so I can see exactly what takes you where. Think I need a little more of the before and after of the "IF THE RESISTANCE IS BELOW 5 OHMS OR 100 OHMS".


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