Checking For Short Circuit to Ground

Short Circuits
Checking the circuit as shown will detect circuit malfunctions that are providing an unintended current flow path to ground (GND). Covered here are two methods of troubleshooting a short circuit to ground (GND). Testing with an ohmmeter and testing with a test light or voltmeter.

CAUTION:
Always use a digital (low current) meter. An ohmmeter, or the Ohms scale of a multimeter, measures resistance by passing a small amount of current through the circuit or component being checked. Improper testing may damage sensitive electronic components.
Direct contact with meter probes at the connector terminals can easily damage the small contacts, causing poor connections and risking future intermittent malfunctions. Special Tools include adapters for making test connections safely and preventing connector damage. See Tools and Equipment.

Testing With An Ohmmeter (Multimeter):

Testing For Short Circuit To Ground:

The example used here is a short that is causing a blown fuse in the circuit powering the license plate lights and the glove compartment light.

Step 1 - Remove the fuse
Step 2 - Disconnect the load (powered components) to eliminate the circuit's normal path to ground (GND)
Step 3 - Connect the Ohmmeter as illustrated

Continuity (approximately 0 ohm):
Little or no resistance indicates that there is a continuous conductive path between the isolated circuit and ground (GND), even though all the circuit's normal ground (GND) paths are eliminated. There is a short - an unintentional connection to ground (GND) - somewhere in the circuit.

No Continuity:
The circuit's normal ground (GND) paths have been disconnected, and there is no other connection between the isolated circuit and ground (GND) - no short has been detected.

Testing With An LED Test Light Or Voltmeter (Multimeter)

Testing For Short Circuit To Ground:

The example used here is a short that is causing a blown fuse in the circuit powering the license plate lights and the glove compartment light.

Step 1 - Remove the fuse
Step 2 - Disconnect the load (powered components) to eliminate the circuit's normal path to ground (GND)
Step 3 - Connect the test light or voltmeter as illustrated

Voltage:
If the test light or multimeter indicates Voltage, then there is a complete circuit - a connection to ground (GND) even though all the circuit's Normal ground (GND) paths are eliminated. There is a short - an unintentional connection to ground (GND) - somewhere in the circuit.

NO Voltage:
There is not a complete circuit. The circuit's normal ground (GND) paths have been disconnected, and there is no other connection between the isolated circuit and ground (GND) - no short has been detected.