I was just going to say the same thing. Pick one circuit and start with that. Once that is solved, we will see if we need to start over with the next problem. When my students were diagnosing my prepared "bugged" cars, they learned very quickly that "run a new wire to replace the one with the short" was not an acceptable answer. We need to find the exact location and cause of the problem, and fix it there for exactly the reason Saturntech9 described. A wiring harness could by laying on the sharp edge of a metal bracket. It could have fallen down onto hot exhaust parts. It could be rubbing on body sheet metal as the engine rocks back and forth. In all of those cases, it's just a matter of time before the same thing happens to the next wire. You can avoid the heartache of having to do the next diagnosis by correcting the cause right away.
I am not sure on the wiring diagram which fuse is blowing, but using the light bulb in place of the fuse still applies. You need to do whatever it takes to power up the circuit, then the bulb will be full brightness as long as the short is present. If the harness is rubbed through and a wire is grounded by the fuel rail, all you need to do is disturb that harness. You will see the bulb flicker when you do anything that causes the short to go away momentarily. By "disturbing" the cause of the short, I do not mean yelling at it! :) I mean moving the affected wire or unplugging something that isolates the short from the fuse box. For example, even though it is very unlikely, if one injector was shorted, the test bulb would go out as soon as you unplugged that injector. Before you got that far, the bulb would also have gone out if you had unplugged the large harness going to the entire engine. At that point you'd know you were on the right trail. You would narrow it down by unplugging each injector until you found the one that made the test bulb go out.
(Actually, this is a bad example because a shorted injector wont cause the test bulb to light up. The injector's circuit is turned off inside the engine computer until the engine is running, so until then, the circuit with the short is not turned on. You would need to have a shorted injector and a shorted driver circuit in the computer at the same time, and neither is very likely).
Similarly, suppose the test bulb went out when you unplugged the large "bulkhead" connector at the firewall. Those usually have up to sixty wires, and many of them feed circuits in the inside fuse box. The procedure now would be to reconnect that bulkhead connector so the short comes back and the test bulb is bright, then remove one fuse at a time from the inside fuse box. When you find the fuse that makes the short go away, you will know which circuit to continue following.
Sunday, November 27th, 2016 AT 7:29 PM