Recently a D2 of mine has been failing to start.
Key illuminates all dash lights, turn to crank and nothing. No click, no sound, nothing.

newer battery. Can confirm adequate voltage
New starter say 4/5 years ago.

The cable from battery to starter selinoid is clean & tight, as is the battery terminal connections.

there is a small red wire with a pinch blade connection to the back/bottom of the starter. It appears to be wrapped in a foil heat shield. If I apply pressure to that connection - as if it’s sliding off slightly- truck fires right up strong.
Im leaning towards maybe mice? Tearing at the foil shield and tugging the connection loose just enough to have an issue? Seems far fetched - or does it?

My question is has anyone else had similar issue?
I want to say that red wire is part of some sort of ignition circuit for alarm or lockout in the event of theft or break in?

 

The small wire what actually fires the solenoid. It sounds like you need to remove/clean/replace that connection.

 

Yep I’d just replace the connector or crimp it tighter.