CHECK A GROUND CIRCUIT FOR AN OPEN USING A 12-VOLT TEST LIGHT

1.	Turn the ignition off.

2.	Disconnect the wire harness connectors of the components that contain the ground circuit suspected as containing excessive resistance.

NOTE: Check connectors - Clean/repair as necessary.

3.	At this time leave all in-line connectors connected.

NOTE: Before inspecting any circuits, first test the 12-volt test light. Connect the 12-volt test light to battery ground or to any other known good ground. Touch the lead of the test light to Battery +. If the test light is good, it should illuminate brightly.

4.	With all the component wire harness connectors disconnected, connect the 12-volt test light to Battery +.

5.	Use the test light lead to lightly probe the ground circuit in the harness connector.

Does the test light illuminate brightly?

Yes

The suspected ground circuit is not open or the condition that originally caused the open or excessive resistance is not present at this time. Another way to check for an open would be to use an Ohm meter and measure the resistance of the ground circuit. While continuing to measure the resistance of the circuit, wiggle the wire harness and connectors to check for an intermittent open or poor connection.
Use the wiring application as a guide to trace the circuits and look for any in-line connectors where the open could occur intermittently.
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the related wire harness connectors.
Perform any Technical Service Bulletins (TSBs) that may apply.

Repair the open in the circuit between the two wire harness connectors. Use the wiring application as a guide to trace the circuit and look for any in-line connectors where the short could occur.
One way to help isolate the open is to disconnect any in-line connectors and measure the resistance from one side of the in-line connector to the matching component harness connector. If the open goes away, the open is on the other side of the in-line connector.