A quick trick is to plug in a pair of spade terminals in place of the blown fuse, then use a pair of small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is powered up and the short is present, the bulb will be full brightness. When you unplug something or move a harness that temporarily removes the short, the bulb will go out or dim.
Most likely the short will only be in the circuit when the automatic shutdown relay turns on. That occurs for one second after you turn on the ignition switch which is enough time for the fuse to blow. That relay doesn't turn on again until you crank the engine. Instead of trying to do the troubleshooting while someone is cranking the engine, it's easier to bypass the ASD relay with a stretched out paper clip. Remove the relay, then jumper terminals 30 and 87 or the two terminals with arrows in the pictures below.
When the bulb is full brightness, disconnect the ignition coil(s), injectors, and oxygen sensors. If the short is gone when you unplug an oxygen sensor, look for a harness that is laying on hot exhaust parts.
Tuesday, July 19th, 2011 AT 5:53 AM