No Electrical power battteries 100%???

[Tarm]

First post been a reader for yrs since I bought this square body.

Truck was garage kept owned by a senior until he pasted away and I bought it.
Truck is in very good shape other than paint.

The truck is for my daughter she loves older square bodies and similar.


Sorry for this being rather lengthy I wanted to insure all details and info was given. I apologize if its overkill

She calls me the other day says everything was fine she parked came out 4 hrs laters and no power. I figured dead bat. Got there a couple hours later and sure enough no electric power to anything. Hook up jumper and nothing. Hmmmm???

I go home and come back next day with tools. Open the door and interior light is on shining bright. Power 100% to everything. Starts right up and works 100%


Get it home and park it. As she stays local I told her to drive it to see if the symptom comes back so I could better diagnose. She comes in and says truck is dead again.

No power to any accessories : lights, radio, climate, starter. Battieries fully charged.

I go out next morning to start working on it. Light is on and everything working.

I check normal things like obviously battery term and cable etc.

Go back in and do some searches on here as I am new to older Chevys had mainly Ford diesels. Find a few threads on here and others.

They seem to indicate the firewall mounted octagonal shaped junction box with two lugs inside of the brake master cyl. From what I read for at least the yr trucks it was stated all power to the cab runs thru that block. Also fusible links and grounds were mentioned.

The junction box looked fine but to be sure I pulled all the connect off it and was going to pull it from the firewall. But I look in the cab where I left the light on to notice if a loose connection triggers it going out. The light is shinning??? I guess I just learned that on 1983s at least with 6.2 diesels all the power does not run thru this junction box or the light would be out. I deducted this would rule this as the site of the issue and all the terminals looked good anyways.

I looked at the grounds I could find. Off the passenger side battery ( diesel dual bats) I have a ground going to frame and another ground wire on the same stud on the frame going up to the radiator support frame I guess you could call it. I also found the typical non shielded/insulated factory flat braided wire going from the block to the firewall. All of these looked fine. No: fraying or burnt sections, corrosion, connections seem tight.

I thought about the fusible links but in my experience which is limited they are a case of working or burnt thru so either continuity or open not intermittent. Correct or incorrect I do not know???

With the interior light on and wiggles and tugged on various wires and connections but nothing triggered the no power condition.

The one spot I have left to inspect is the starter terminal connections and wires. My question is how could those connections effect all power in the cab as well.

When the power is dead no accessories work period.

I also have a bit of a issue with the neutral safety switch as the spring in the shifter broke and so you have to sometimes hold the shifter a bit to the left in park to get it to disengage and allow the starting. But it has never had any effect on anything but neutral disengagement and no effect on the current condition when it was happening.


I am at the point where I feel I have gone thru the search functions a good bit and tried the comments and suggestions found there.

I would be very appreciative for any help or suggestions anyone could offer.

I have never had a condition like this that did not have a obvious ground fuse or wire connection that was found quickly.

I have noticed that the in cab fuse box is mounted to the rear at the firewall. Could a moisture or ground there be the issue. I thought I recalled someone mentioning issues with water getting in and effecting the fuse box given its mount location. The thing that has me stumped is that it comes and go but is functional when it comes back its not effected when a load is put on it. Normally if this happened and the power came back I would expect when I tried to start it power to go back out and not allow it to start. That would also possibly indicate a weak feed side (positive) issue if grounds were good. But with it going back and forth between no power and everything is good not sure where to proceed to.

As here in this area we have dealt with lots of on and off rain this summer and into fall and was the case on these days it happened I was thinking of pulling out the garden hose and hitting all around the firewall etc and seeing if I could trigger the condition.


Again any help greatly appreciated. My trucks spec are below in my sig.

Thanks again for any help anyone can provide.