Truck Repair: 1991 FORD BRONCO NO START, ford bronco, first ford

Question
MY BRONCO WON'T START. WHEN I TURN THE KEY, I HEAR ONE DISTINCT CLICK, AND THEN ALL THE OVERHEAD LIGHTS IN THE CAB GO OUT. THE SAME THING HAPPENED TO ME YESTERDAY, BUT I CLEANED OFF THE BATTERY TERMINALS WITH COCA-COLA AND IT WORKED ALL DAY AFTER THAT. THIS MORNING THOUGH, SAME PROBLEM AS THE DAY BEFORE. I HAVEN'T TESTED MY BATTERY OR ANYTHING YET, BUT I DID BUY A NEW BATTERY YESTERDAY WHEN I WAS ORIGINALLY HAVING THE PROBLEM, AND THE SAME THING HAPPENED INITIALLY WITH THE NEW BATTERY, SO WHEN I GOT IT RUNNING I SWITCHED OUT THE BATTERIES AGAIN AND TOOK THE OLD BATTERY BACK TO WAL-MART. THIS IS MY FIRST FORD AND SOME OF THE SET-UP IS A LITTLE STRANGE TO ME, SO ANY HELP YOU CAN OFFER WOULD BE APPRECIATED. THANK YOU  

Answer
Hello Matt,
It sounds like a starter to me, but I would recommend clamping a load draw tester around the cable and see first.
Most major parts houses will test it like that on the vehicle for you.
I assume you removed the cables and cleaned inside the cable ends to bare metal, not just shiny black scale?

Van