The closest book I have is a '99 book but it should be similar to your truck. The fuel pump is on a different fuse and totally different circuit, so you should still hear it hum for one second each time you turn on the ignition switch. That leaves him out as a suspect.
The alternator isn't likely to short intermittently. The 12 volt feed brush could potentially be damaged during a repair attempt but even that is hard to do. I would not suspect the alternator, at least not until everything else has been ruled out.
That leaves the ignition coil and one of the injectors as suspects. The fuel system leak detection pump and oxygen sensor heaters are on a different fuse, fuse "A", a 20 amp after the ASD relay. That would be the one that would blow if the problem was with those items. That circuit won't stop the engine from running. Since this is an intermittent problem, you might consider removing that fuse, then see if the 30 amp fuse still blows. If not, it could be because the 20 amp circuit is shorting but the 30 amp fuse is blowing because it has more current running through it for other stuff. Removing the 20 amp fuse will cause the Check Engine light to turn on, and fault codes will be set in memory, but you should be able to drive the truck.
If the fuse that's blowing is the 30 amp fuse "3", that pretty much leaves the ignition coil and one of the injectors. Chrysler has very little trouble with injectors so I guess I'd head for the coil first. No professional likes throwing random parts at a problem but if you have another coil to install, you might try that first. Another plan of attack would be to remove the dark green / orange wire from the coil's connector and use jumper wires to hook in a 10 or 15 amp fuse. If the coil is causing the problem, that's the fuse that will blow.
The only other place that circuit goes is back into the Engine Computer so it has proof the ASD relay turned on. If the 30 amp fuse still blows, we can rule out the coil. I think I'd be looking for a wire someplace that's rubbed through and grounding out. If you can make the fuse blow by wiggling and moving wiring harnesses around, remove the fuse and use jumper wires to replace it with a 12 volt light bulb. Brake lights work well. The bulb will be full brightness when the short is present in the circuit. The coil will have to be disconnected because it is normally grounded by the computer. Woops. I have to back up here. Put a new fuse in, then put that brake light bulb in place of the ASD relay. That relay won't stay on by itself unless the engine is running. Check the coil first, then if that doesn't pan out, I can provide more details on the light bulb trick.
Tuesday, January 25th, 2011 AT 11:16 PM