Testing Ground and Low Reference Circuits: Notes
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The testing of ground and low reference circuits can be performed in multiple ways using multiple tools. Ground circuits may be tested in the following ways:
- Measuring resistance with a DMM
- Testing continuity with a test lamp
- Measuring voltage drop with a DMM
Each method of testing a ground or low reference circuit requires attention and understanding of the tools and results to ensure misdiagnosis does not occur based on the results:
- A DMM requires a more specific set of conditions on the vehicle when testing, but will accurately measure resistance. A DMM may not identify a ground or low reference circuit that maintains continuity, but is damaged and has compromised load carrying capability.
- Testing a ground or low reference circuit with a test lamp is a good way to quickly determine continuity, but may not identify all instances of excessive resistance.
- Measuring voltage drop with a DMM is a very accurate way to test a ground or low reference circuit, but requires the most time and effort to access components and ground locations.