The next time it won't crank, try to have someone else turn the switch while you listen under the hood. Better yet, put your finger on the starter relay to feel if it is clicking. If not, look at the clutch switch under the dash. You can unplug it and bypass it with a paper clip between the two wires in the connector.
If the relay clicks, the problem is with the starter solenoid or wiring. It's more common to get one loud clunk out of the solenoid, but it won't crank if the contacts are worn away. This is a common issue with the little Nippendenso starters. The contacts can be replaced quite easily and inexpensively.
Another common problem, although usually not intermittent like yours, is a cracked cam on the end of the ignition switch cylinder. When broken, it will turn far enough to turn on the dash lights, radio, etc, but won't go quite far enough to get to the "Crank" position. There is a repair kit available from the dealer for that problem. It's a real cheap fix. This problem will cause the starter relay to not click.
If the starter relay doesn't click, and you're desperate to get going, you can jump across the starter relay while the ignition switch is in the "Run" position. Be sure the transmission is in neutral or the truck will leave without you! If you have a square relay, about 1" x 1", disregard the two parallel terminals on the sides and the terminal in the center. The center terminal isn't used. The last two form the letter "T". Those are the two to jump in the socket, (relay removed). A paper clip works fine.
If you have the smaller rectangular relay, about 1" x 5/8", it's the same terminals you need to jump, but they don't look like the letter "T". There are three parallel terminals. Disregard the two outer ones in the corners; those are the coil. You want the center one and the one on the other side of the socket. Again, the center terminal isn't used.
Don't just poke around with the wire or paper clip in the hopes something wonderful will happen. One terminal is grounded through a wire, (manual transmission), or neutral safety switch, (automatic transmission), and one wire comes directly from the battery. If you jump those two, the smoke comes out and can't be put back in! Usually the paper clip will get red hot before damage occurs to the wires, but it's still embarrassing. To avoid heart break, just stay away from the two parallel terminals in adjacent corners of the socket.
I suppose you could have a defective starter relay too although that's not real common. Try switching it with another one such as the AC compressor or trailer tow relays. By the way, the relays are in the Power Distribution Center under the hood, near the battery. There will be a cover you must remove.
Saturday, April 25th, 2009 AT 4:47 AM