nspctr1 said:
OK, that helps. Pull up the schematic for the '78 FJ40 in tech links and take a peek.
Here is a link:
http://www.yankeetoys.org/documents/wiring_diagram_78_fj40.pdf
The Acc and Start labeled positions and their attached wires in the upper left corner of this diagram are flipped, so don't let that trip you up.
Starting at the AV point of the switch, follow the white wire with light blue stripe (WL) wire and notice that it goes directly back to the battery and alternator through the amp meter. If the short was in this wire, the wire would always smoke without the key on. This tells you that the short has to be after this wire where it connects to the switch. Notice the LR wire (mislabeled BW) that goes to the accessories at the very top which goes to the radio fuse. When you turn the key to this posiiton the 10 gauge white/blue stripe wire that goes to the key smokes. The LR wire is a small diameter wire which would burn before the large White wire with a blue stripe. This tells you that the short can't be in this wire or it would have burned up by now. This strongly suggests that the short is in the switch itself. You just have to get in there and dig to replace it.
If you have wired the fuel pump to the accessory position of the switch it could be the problem, but again if this wire is smaller than the one that smokes, it is not the problem.
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