Thank you for providing good observations and information.
You can rule out the fuel pump circuit since you hear it run for two seconds when you turn on the ignition switch. That leaves the starter solenoid or something coming off the ignition switch. Start by removing the starter relay, then turn the ignition switch to "crank". If the fuse doesn't blow now, inspect the 14 gauge brown wire that goes to the starter.
If the fuse still blows, start by inspecting the wires that plug into the ignition switch. There has been a lot of trouble with contacts and wire terminals overheating. Look for the yellow 16 gauge starter relay wire and the black 20 gauge ground wire melted together.
The yellow wire to the starter relay coil is the only one coming off the ignition switch that is only hot in the crank position. All the other ones on this circuit are also hot in the "run" position. Since the fuse isn't popping in the run position, that leaves them out.
Basically that leaves the two halves of the starter relay. A quick way to figure out which circuit has the problem is to manually bypass the contacts without activating the coil circuit. You can use a paper clip or piece of wire to jump the two terminals in the relay socket, or remove the relay's cover, reinstall the relay, and squeeze the contact. If the fuse pops, the brown wire to the starter solenoid is grounded or something is shorted inside the solenoid. Unbolt or unplug the small wire from the starter and try it again. If the fuse still blows, the wire is grounded.
The two terminals to jump are #87 and #79. If they aren't marked, disregard the two parallel terminals on the sides, (those are for the coil), and disregard the center one. It isn't used. The two remaining terminals form the letter "T". When you connect those two, the starter should crank.
If it does crank, and the fuse still blows when the ignition switch is in the crank position, and the relay is removed, there are only two possibilities. The yellow 16 gauge wire is grounded or there is a shorted terminal inside the transmission computer. After a connector, the wire turns into a yellow wire with an orange stripe. Pin 8 of the transmission computer gets 12 volts on that same circuit as the starter relay as a signal to stop certain processes during cranking.
As for the heater, the two heater hoses should be too hot to hold onto for very long. If they are not, try back flushing the heater core with a garden hose. If they are hot, suspect a problem with the HVAC computer or an actuator on the heater box.
Monday, January 11th, 2010 AT 3:12 AM