This has just started recently; turn the ignition key to start the engine and I hear a little click and nothing happens. The engine never cranks. And it's very random. Sometimes it will start fine for a few weeks. Sometimes it will only do it one time and sometimes it will do it a few times in a day.

Here's what I see:

1. I have full interior lights, gauges and etc. I've got full headlights also.
2. On my Scangauge-2 when I twist the ignition key I see the voltage drop to 11.5v. I also see it sometimes drop to 10.5v but it doesn't drop that far consistently. It will and will not start if the gauge shows 11.5v so it's very intermittent.
3. I'll jiggle the key a few times, turn it off and then try it again and the engine may or may not crank.
4. When the engine does crank it turns over like it has a good battery in it (i.e. nice and quick) even with the gauge showing 11.5v.
5. The alternator is charging at 14.2v on first start and at 13.9v when engine is hot and all accessories are on.


Here's what I've done so far:

1. Tested the battery with both a Load Tester and a Solaris Electronic Battery Tester. Both of them say the battery is completely fine (12.7v / measuring 600 CCA). However the battery is approximately 3 years old.
2. Checked the connections on the starter and they are solid and secure.
3. Cleaned the connections on the battery (they weren't bad to begin with).
4. Checked the cables for corrosion and found none.
5. I keep forgetting to check and see if the Theft light is flashing fast or flashing at all.
6. Swapped the starter relay with the cooling fan relay. No change.
7. I do keep it plugged into a battery tender while I'm not using it. The truck will sometimes sit for a few weeks before
I drive it again so I like to keep it charged.

What else could I check to help me determine what's failing?

 

As one who is on starter number three( original lasted 10 yrs and rebuilt 4 yrs) that's my guess. Probably the solenoid that's attached to starter in your case. Both times there was nothing intermittent on mine. When it fails you can't even get it to start with a jump.
Both times had to be towed.

 

Thanks Maz. I'm hoping it's not the starter. The PO said he replaced it about a year before he sold it to me and it does look "new'ish". But it looks like a real pain in the rear to replace.

I've got a few tests I'm going to run and see what I can find. The problem is so intermittent that it makes it hard to figure out.

 

It's a pain alright. Need to jack it up,remove tire and inner fender. If you do have to remove it the bolt on bottom where neg cable attaches has two nuts.One to hold on cable, the one below holds starter. Need a wrench to hold the lower nut in place while using socket to remove top nut to get cable off. Wish i had remembered that prior to messing up cable lug.