The driver said it some times he would have to turn the key several times before the starter would work. The dealer shop said the batters were bad and replaced them. I replaced the starter and switch. Then the driver ask me to install a push button. I did this wireing it directly to the starter like you would a remote test starter switch. The day i did this i found it had a starter relay in the fuse box so i replaced it. For about a month it was fine i thought it was the relay but this morning it wouldnt turnover after several trys with the key then he tryed the button and it didnt work but after several more trys it started. When he got back I tryed it several times and it would not turn over sometimes after starting it several times with the key but the next time it would turn over. I found 1 battery nut that was worm after all the test starts. I cleaned all the terminals and load tested the batterys today. The cable ends and battery bolt posts had a film on them. The truck has 350.000 miles. It has 2 hot and 2 grounds from the bats to the starter.