Sorry to break in with another Ranger doing the same thing, but mine is, and it's a bit weird. OK, so it's a 96 4.0 V6. Bought it used before last winter. I bought a used battery soon after I bought the truck.
Everything was fine until just after I had some brake lines replaced. Drove it home from the shop, no problem. A week later our temps dipped into the teens. I went out to start the truck (hadn't touched it in the past week), and got Rrr rr, then nothing. Turned the key again and got a single click and nothing else. I figured the cold and a used battery meant the battery was weak. So I got out the charger, and left it charging while I went to our usual Saturday shopping. The truck was locked and the hood was mostly closed while I was gone.
When I got back, a few hours later, I decided to check the truck to see if I could get it started. I decided to open the hood first (truck was still locked). The theft alarm went off (didn't know it would for opening the hood). I unlocked the door and the alarm went off. Tried to start the truck and just got a click. Turned the charger to the 'start' setting and tried again. No change. Checked the headlights and they were fine, but didn't dim when I tried to start it.
Since the lights were good, I thought the starter was the likely problem. So I replaced it. Nothing. Decided to check the battery cells, and found 5 nearly dead and one good. Replaced the battery (after 8 hrs charging @ 2amps), and had to replace the negative clamp in the process. No change. Verified that the headlights were on strong, dimmed very slightly when I tried to start, but the starter still went click once and nothing else.
Figuring the problem is either the relay or wiring connections, I tried bypassing the relay. I hooked a jumper cable directly to the + terminal on the starter solenoid and the battery + post. Turned the key and got the starter turning weakly. So the starter is OK, the engine isn't seized, but there's still a problem. Also, the cable got fairly hot after a few attempts. Now I'm thinking it's the relay and a weak ground connection or something. So I replaced the relay, and disconnected all the wiring for the starter. At each connection, I cleaned off the contact points with a degreaser, sanded clean with fine sandpaper, and put on some dielectric grease, and put things back together. So all the starter contacts, the wiring connections at the relay, and even cleaned the + battery clamp and used some dielectric grease on the battery clamps. No change.
So I'm wondering what's left. I could have a bad wire somewhere. But is it possible that it has something to do with the anti-theft system? There's no button I could find under the dash to reset the system. I don't have the remote entry key, so I can't try that. But I've unlocked the doors and tried the ignition many times since the alarm went off. So it should have shut the system off. But if I try the ignition twice in a few seconds (like on - start - back to on - back to start - in 10 seconds or so), the doors lock and unlock. I've never had a car/truck with an anti-theft system before, so I don't know how normal that is.
I did check all the fuses for the alarm and starter systems, and couldn't find anything wrong there. Any suggestions before I give up and have it towed somewhere?