Got my truck back from bodywork (rocker panel fix).
I tried my remote start and for some odd reason my truck eng turns but does not start. This only happens if the A/C or heat is on, if I turn the system off the and try the remote start the truck starts right up.

I also notice that my trailer tow lights don't work. (not sure if its related)

 

Weak battery and the blower motor pulls enough power off the battery to not have enough "juice" to start the engine

 

Thanks I'll give that a check for sure....but the eng turns over at the same speed in A/C mode or off mode.

 

I've noticed on occasion that strange things happen when the battery is weak. Even though the starter may turn the engine at nearly the same speed. My guess is the drain of the starter causes enough of a voltage drop across the battery to effect the start process. Like possibly weak spark at the plugs.