How To Determine A Short Circuit

With test light:
Connect a test light (rated at approx. 3 watts) in place of the blown fuse and allow current to flow through the circuit. Disconnect one connector at a time from the circuit. Starting with the one located farthest from the power supply. If the test light goes out when a connector is disconnected, the wiring between that connector and the next connector (farther from the power supply) is shorted.

Fig 1: Checking Short Circuit (With Test Light)
Courtesy of SUBARU OF AMERICA, INC.
With ohmmeter:
Disconnect all affected connectors, and check continuity between each connector and ground. When the ohmmeter indicates continuity between a particular connector and a ground, that connector is shorted.

Fig 2: Checking Short Circuit (With Ohmmeter)
Courtesy of SUBARU OF AMERICA, INC.