Take the cable off and remove clamp if it is an aftermarket one that has been added on. Put about a teaspoon of sodium bicarbonate in a class of water and soak the cable end with it. You will see it react and remove the corrosion. Then brush it off and rinse it off real good. Do the same to the battery post, being careful not to get the stuff in the battery itself. While you are at it check the battery box and see if it is corroding as well. Same treatment. Then give the reattached connection a light coating of wd-40. It will stop further corrosion.

OK, went fishing the other day, hopped back in and click. Had the recommended wire and volt meter ready for this, and the voltage was showing a very quick drop from 12.6 to zero while clicking. Put the jumper cables on from my buddy's car and it fired right off. I drove straight to Toyota and ordered a real Toyota reman starter which I just picked up this morning, so at least I will continue with a worthy starter. Hopefully I will have time to install tonight and we'll go from there...

Well, if the voltage you measured is dropping to zero, that means that something is wrong between the starter solenoid and the battery (i.e. wiring, connections, switches, relays, etc.). What that is telling you is you have excessive resistance someplace in the circuit feeding the starter and that resistance times the current trying to flow to the starter is causing a voltage drop. So a new starter is unlikely to help.

Would kind of like trying to run a big V8 engine with an eyedropper feeding fuel to it. Sure, the engine would not run, but not because of a problem with the engine, rather that it is not getting enough fuel.

Sounds like the neutral start switch is to blame.

I'm not that familiar with autos, but see if you can jump the switch, if it works, thats your problem.

Well, the solenoid wire goes up into a factory wrapped loom under the intake and throttle body and up through the firewall behind the dash. Any better way to check this stuff without taking half the dash apart to trace it? I can take the solenoid wire off the starter and just check the voltage applied to it when I hit the key- never has been suspect as I've always got 12.4-12.7 volts.
As far as the neutral switch goes, I can only start the truck in neutral and park; no other gear selected lets it start. I thought this would signify it as working properly, do I need to do some type of continuity check on it as well?

Hope Toyota takes this starter back!

I'll look to see if I have another, I only replaced the battery to the block wire so I'll look for the one you suggest.

Well, 2 options are:

1. See if you can locate some good test places where you can check voltages between the starter and the ignition switch to find where the problem lies.

2. Do one of the following:
- http://www.4crawler.com/4x4/CheapTricks/Starter.shtml#OtherOptions

I installed a separate relay to power the solenoid as I figured it was easier to do that than to trace the factory wiring back to find my intermittent starting problem. Since installing the relay many years ago, it has started on the first turn of the key every time.

I think I will install the reman Toyota starter. I just got the click when I went to go start the truck again. Line voltage from the ignition switch was never under 12.0V with over twenty turns of the key. When I hooked up the 4Crawler solenoid test wire I made, I got 5.2V with each solenoid click. I unplugged all of it, took a small jumper wire and breifly connected the + post of the starter and the solenoid terminal and it fired right off. I think the solenoid must be intermittently shorting...

Your test precisely describes a high resistance issue in the wiring to the solenoid. Why?

1. Measured 5.2 volts under load. Something is causing a ~7 volt drop in the factory wiring.

2. Direct connect solenoid to 12 volts and it fires right up. This means you bypassed the factory wiring and it worked fine.

Put 1 and 2 together and that says w/ factory wiring = problem, bypass factory wiring = works.

Solenoid is not shorting out, if it did you would have lots of smoke and more problems. Realize the solenoid does pull about 20 amps (and yes I have measured that) and that is a fair bit of current. Using V = I * R, with I = 20 amps, for a 7 volt drop you only need to have 7/20 ohms = 0.35 ohms of resistance in the factory wiring to cause a 7 volt drop. 0.35 ohms is not a lot, many ohm meters will not even measure that low.

Thanks for all the assistance Roger! I'll see what I find with the wiring from the switch to the solenoid.
The only thing I'm having a hard time wrapping my brain around is the fact that is intermittent. If there is resistance and voltage drop in a specific wire, why is it not constant?