(crossposted)
Firstly thanks for the ad,
I have a 94 e150 it was running fine recently replaced firewall solenoid, then after a short time there was a burning smell and it had melted the solenoid on the starter, then everything went dead. I'm going to list everything that I've checked and that is working so please look at the list carefully rather than constantly make suggestions about things I've already tried, thanks.
Battery and battery connections are good, ground to body is good ground to engine is good, fusible link is good, all fuses under the hood are good all fuses under the dash are good . replaced starter solenoid replace firewall solenoid replaced actuating wire to the starter , the main power cable to the starter is good. I've cut into the wiring harness running under the engine to the starter looking for a short didn't see any obvious signs of it the trip wire going to the solenoid was bad hence the replacement.
So am I looking at a PCM problem? Again I have no power anywhere just prior to shutting off the headlights would not work if the engine was not running I only had exterior lights with the engine running ,then everything shut down.
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Do you have any kind of test equip to use, if so what?

What was the original problem?
I have some idea of what may be wrong, but to save a lot of trouble need to know as much info as possible.