Jakay

Mediocre home mechanic action going on here. Also cross posted from https://www.f150forum.com/f6/1990-xl...7/#post7563202 because of temporary brain deadness.

So, when I turn the key to ON the dash lights up, everything seems good. But when I turn it to that bit further into the spring aka START all charge goes away and it doesn't ever register any charge again, no dash lights, etc. If I disconnect and reconnect the battery we're back to square zero, and everything lights up in ON again.

Of course the ignition switch seems like a good starting place and I have replaced it fairly recently, but it was starting and running fine on it, and even after just checking it again it seems fine. All the fuses are good too, although I wouldn't suspect a regular fuse given how its acting.

Worth noting, the starter isn't even trying once. The last thing I did in general was cleaning the IAC valve.

I need a truck this year and I need to know if I can even get this one running again. Worst case I'll tow it to a mechanic but if any one has any ideas of what this could be I'm game to try a few more things out. Getting into the electrical here and all the relays and everything isn't exactly my forte. 12.X V is coming across the battery, and through the first relay it looks like (or whatever that is bolted to the side frame just behind the battery, which has been a problem in the past).

Dunno, perpetually sitting on "is it worth it" with this one. This specific behaviour is hopefully something someone here has seen in this exact way. This forum has been good to me, and I always appreciate the responses.

Soup Bean

Clean the connections at your battery terminals and your fender mounted starter relay (aka solenoid).
Look at the strands of wire that are visible, between the insulation and the terminal ends of the battery cables. Are those wires corroded? They may need to be replaced.
Check the condition of the cable that runs from your battery negative terminal to the front of the engine block. How is that cable? How clean are the surfaces where it connects?
Wire brushes or 60 grit sand paper are good ways to clean electrical connections, then make sure they're reasonably tight. You can break battery terminals and relays by over tightening them, so stop when they're reasonably tight.

Jakay

Thanks Soup Bean, great advice. Also finally I know what the solenoid actually is and what that relay is (they've been just terms to me until now, turns out they're one and the same).

There is, needless to say, quite a bit of corrosion going on. This truck sits outside in the Pacific Northwest, it would makes sense that corrosion in a cable somewhere is to blame. So far everything running in and out of the solenoid it self looks pretty good. Like corroded, but showing a thru charge (which maybe it shouldn't be). The starter is in a pretty difficult spot to reach with my current multimeter, I suppose working a wire down to there is the next step, if I don't just haul it off to a shop (finding it hard to make time for this project).

Appreciate the feedback!

memoniz

Soup Bean is correct. I've had that problem several times over the years. If your battery cable ends are not removable, you can get new ends, cut the cable slightly shorter, strip and expose cleaner wire and reconnect. Do both the ground and positive. This should keep you good for a long while. If the problem appears again within a few months or doesn't work right after you fix it, then replace the whole cable. I fought that issue for years. Every few months it would crop up again. I eventually replace both positive and negative cables, along with the cable from the solenoid to the starter and hadn't had a problem for several years now.

Jakay

It seems like it might be the starter. Solenoid and wire look pretty good.