Hot truck doesn't start

[JD914]

I've been having a really annoying problem with the ignition on my 04 Limited V8 that I'm hoping somebody could shed light on.
Periodically over the last few years, I've gotten into my truck, turned the key and gotten lights, radio, etc, but no ignition. Nothing, not even a click. This could be after it has sat for hours, or only for 30 minutes. I thought it was a problem with my remote starter, since that would start the engine. Being lazy, I'd simply use the remote starter whenever I encountered this.
Since my truck was broken into and the remote went missing, I emailed Astrostart, who said that it's actually the ignition wiring, as the remote starter is positioned between the ignition and the starter. (I've also found somebody else with a different vehicle with a similar problem)
I've recently noticed that this only occurs when it's hot out (NEVER happens during the winter here in SoCal), and only when the interior of the truck is hot, not necessarily the engine bay. If I open the doors and let a breeze through, the interior eventually cools and the truck starts up as if nothing happened.
Has anybody experienced this? Could anybody point me to a wire or relay inside the vehicle that could be overheating? Shift position sensor maybe?

 

[4RunnERD]

Several years ago I had a similar problem with my 88' Trans Am GTA. Except mine was egine heat related. It would never start when it was hot. It got really annoying to drive somewhere and then have to wait an hour or so for the engine to cool off enough to start it up again. A mechanic eventually told me there was wire within the starter itself that when it got hot curled up and away breaking a connection needed to start the car. Once the engine bay and starter cooled off, the wire would cool and come back to its normal resting position making the connection again and that's when I could finally start my car. I replaced the starter with a high torque version and wrapped a heat sheild around the starter and never had the issue since. Maybe something similar is going on, but with an interior wire in your case. Not much help I know, but I feel your pain.

Maybe you could start by following the wires from the alarm system itself, if you know where its mounted, and trace them as far as you can to see if there are any lose connections or something that doesn't look right. I would imagine the brains of the alarm are mounted under the hood or under dash somewhere and you might be able to pick it out as a non OEM part if it is an aftermarket alarm. Also, you mentioned that your car got broken into (sorry to hear that). Is it possible that something was damaged during that? For example, if they stole a head unit or something maybe a wire got mucked behind the dash somewhere? Good luck and let us know what you find.

 

[JD914]

Unfortunately, Astrostart doesn't give install instructions, and their closest dealer is in Utah, so I'm going to have to try finding the brains myself, which should be fun.
And I've had this problem way before my truck got broken into, so that's not it, unfortunately.
And I'm supposed to be going to the desert this weekend!

 

[JD914]

Found the brain, but also have a replacement remote on its way, just in case.
I'll dig into the dash this week, and give an update. I know there was somebody on the forum who had a similar problem....

 

[4RunnERD]

That's good. Where were the brains hiding?

 

[JD914]

They're just hanging out of the lower dash, over the gas pedal. I had seen it before, but had no idea what I was looking for, so didn't realize that the problem could have literally been hanging in front of my face (well, at least in front of my face when my laying in the footwell).