Elcctrical Short's got me Stumped

My battery died ('89 SC) and had to boost it-the car started and ran then died and the battery area started smoking. One of the bigger wires burnt through right at the starter relay (positive connection). I fixed the wire, got a new battery and found that a bunch of stuff isn't working (radio (lcd comes on and you can tune it but no sound, power door locks and seats, tail/brake lights, high beams). Checked all the fuses and found the following burnt out:
1. in the under hood panel-Cavity C - protects the fuse panel - not sure what "fuse panel" means - the under dash panel? what components)
2. under dash panel-Cavity 16- rear park and license lamps, Cavity 17 - LCD illumination Relay (anyone know what what/where this is), Chime, front park lamps).
I replaced all those fuses and Cavity C and 17 burnt out again. Tried to find the short (I'm a real novice on this) - I measured 12.5V across Cavity C (don't know if this should be the case). Disconnected the battery and tested for continuity across Cavity C while disconnecting wire harnesses inside the car under dash all the way to rear end - continuity always present.

I've spent about 10 hours on this and before sending it to the shop was wondering if anyone has some ideas. Thanks.

Check the Relay and fuse panel under the hood. Also check the fusable links that connect to the starter relay. They may not looked burned. Use a meter.

Jeff

If the fusible links were burnt-out, some things wouldn't work but if the links were burned why would the new fuses in Cavity C and 17 burn out?

Silverstreak89 said:

If the fusible links were burnt-out, some things wouldn't work but if the links were burned why would the new fuses in Cavity C and 17 burn out?

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One explanation would be that the main light switch or multi-function switch is defective and causing the headlights to be powered through these fuses instead of directly from the battery. That would also explain why you lose your headlights when these fuses blow even though the headlights are not fused.

I agree with JD. It sounds like crossing of electrical circuits. The headlight switch can melt down but all it's connections are "light" related. With the radio, etc going out,

I would suggest pulling the cowling around the steering wheel and visibly inspect the ignition switch. They are designed so they will literally fall apart. There is a large copper slider between the top and bottom halfs that can raise SEVERE havoc when the switch falls apart.

I had a new switch when I found out about mine (BUT had difficulties with the back TORQ screw and after looking at the problem, knew it would happen again) so I just wire tied the two half back together ( added 2 more wire ties for "industrial strength"). Haven't had a problem since.

The light switch, FORD use to sell 2 ways, with and without harness. If you catch it early enough (before the damn thing melts) you can just replace the switch. Otherwise you had to split in the new receptacle and harness with the switch. I rarely use my fog lights to help minimize this. ( lessons learned on 90SC being applied to 95SC).
--Fred