2006 Lariat 5.4L intermittent starting problem
 

In the last 4 months my truck has not started maybe 4 times. Lights come on, starter does not turn over. Just a click. I try 5 times in park then 5 times in neutral then 5 times in park. I first thought I had a drain on the battery because it would start after a charge. Then after checking for drain current I could not find any. Another time it would not start with a full charge. So, probably not problem. In between I had a new starter and solenoid installed. Then had my mechanic recheck the starter solenoid connections. Had him check the Park / Neutral switch which looked OK. This morning it would not start again so I took my wife's car. When I got home she had started the truck and went to the store. I tried it and it started. Nothing was done to it in between. I left this truck with my mechanic for a week once and he could never get it to not start. Can't fix what ain't broke. Battery and alternator test good at NAPA store. In between I had a remote start added. So when it won't start it won't start with key or remote.
Not sure what to start swapping out till it is fixed. Any suggestions on what to check when it isn't starting? Hate to take it to a dealer (45 miles away).
Appreciate any help.

I'd start checking the ground and connections to make sure they were nice and tight and free of corrosion. I'd then check the battery myself. I understand NAPA said it was OK but it's my understanding that these engines are finicky if they don't see a little more that 12V's (ie 12.6V) at ignition.

Sometimes just getting in and having the lights turn on is enough to drop a little voltage below the threshold.

I had exactlty the same problem and I swapped it out for a new battery and voila! Problem gone. I don't know how old your battery is but it may be the source of the headaches.

Good luck!

With the cold weather hitting .. batteries will start acting up if they are close to being at the end of their life.

I'm thinking maybe the neutral safety switch. Try wiggling the shifter next time it won't start. Do this while you have the key twisted to the start position.

I agree with the battery. Might have to low cold cranking amps. Cold weather will definitely affect batterys and as stated these trucks are really picky when it comes to voltage.

What is the in service date stamped on the battery ?

Battery sounds like an easy fix to try
 

The battery in the truck is 3 years old according to the sticker. I know that isn't terribly old but I am looking for items getting close to dying because this is an intermittent problem. Installed a new 850 CCA NAPA battery. Now I will wait to see if the problem goes away. Maybe a month with no problems it will be fixed.
I'll let you know.
As far as the Neutral/Park switch, I thought that was it also but have had mechanic look at it. He thinks it is good. That is why I try to start in both Park and Neutral.
Another item I will watch for if it does not start again is the security system led on the dash. I understand it will flash quickly if the security system is preventing the start. Perhaps a bad key or sensor.
Thanks for your input.

I am also switching to LED lights so the current draw when they come on prior to starting will be significantly lower.

With 850 CCA .. should fire right up with all lights on. hope your good now.

3 years is a pretty good life depending on the battery. My last Motorcraft battery only made it a little over 3 years. I believe the warranty on it was 3 years... go figure.

GTC-

My 2c.

you need to identify the source of the problem when the no start condition is happening. And if I could correct our terms- I think what your complaining about is a no "crank" condition- which of course leads to a no start.

I always like to go to endpoint and test backwards. So if you turn the key and the starter doesn't engage- attach a DVM meter to the solenoids start lug- which I believe is right at the starter. If it's getting 12 volts- then the switch, key recognition, controls and all wires are good- and your starter and it's main 12v source or ground are bad. If you don't have 12 volts there, then you need to trace the controls/wires.

BTW- Are you using a factory key and/or have you noticed if while turning the key, the red light on the dash is flashing when the truck DOESN'T crank? I had (still have) 2 cloned keys that sometimes don't get recognized by the PATS and it causes a no crank condition. Other times the same keys work just fine.