Many intermittent open or shorted circuits come and go with harness and connector movement caused by vibration, engine torque, bumps and rough pavement, etc.
Test the wiring harness and connectors by performing the following:
Move the related connectors and wiring while monitoring the appropriate scan tool data.
Move the related connectors and wiring with the component commanded ON and OFF, with the scan tool. Observe the components operation.
With the engine running, move the related connectors and wiring while monitoring engine operation
If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary
Test the electrical connections and/or wiring by performing the following:
Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body, backed-out.
Inspect for improperly formed or damaged terminals. Test for incorrect terminal tension.
Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body.
Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits.
Inspect for wires that are broken inside the insulation.