The entire content of this post has been deleted. This action was necessary due to the extremely high levels of misinformation contained therein. Specifically, I am referring to the description/images/illustrations purportedly showing the methods used to tap into battery power at the solenoid "B" terminal and the subsequent transmission of that power into the cab and throughout the vehicle.
The information and advice offered here previously; as regards the number of power feeds, associated fusible links, their routing and circuit descriptions,
would have been valid -
if the truck in question was a later model year (1979 +). But it isn't - it's a 1975. There is no excuse for this - a quick look at the wiring diagrams was all it took for the author to realize he was shooting it out his ass.
Up to and including the model year 1978, only one secondary main power feed was used to bring power into the cab from the solenoid. But having said all that, I would still verify first that the fusible links are intact. Using your meter to confirm 12 VDC at the RH (LH looking at the firewall) terminal post at the FW junction block is hot. If it is, you can avoid crawling around under the truck. Next, check the link at the outlet side of the JB. Just use the meter's probe to pierce a small small hole in the insulation.
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If that proves good, well I guess it's on to the cab side of the circuit. But I have a good feeling that the problem will be in the engine compartment. Even though all power comes into the cab on that single lead, once inside it is branched off to three main components: the fuse block, the H/L switch and the ignition switch. So - because you went completely black - I am sticking with the primary power supply as the problem. If it were an ignition switch issue, you would still have had headlights and also several other components that are fused but not ignition switched.
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And Jim, I now agree with you on this:
Fusible link at the starter WILL kill many of the systems.
Matter of fact, I can't think of any circuits that would be powered up if that single fusible link at the solenoid blew - there is no other way for power to go anywhere.
Let this be a lesson to all who seek advice on the internet. "Consider the source". You might very well be reading the words of a babbling idiot, or someone who drank a 12 pack of Natty Ice before signing on - or maybe both.
Mr. Moderator: Please deduct 5 reputation points from my account.
