no start when cold... Help needed!!!!

[Kedzierski]

My 03 ram is not starting when is under 30f. When it is plugged it will start when is plugged in for at list three hours. I replaced my heater relays. Replaced batterys and it is still the some problem. Any advice appriciated. Thanks

 

[p-Bar]

I assume you can hear the solenoids pull down for the grid heater, does your interior courtesy light dim when this happens??

 

[lmills]

Have you tried removing any of the aftermarket boxes? If not, I would start there and see if it helps. I know it is a long shot, but worth a try

 

[Kedzierski]

I jest changed booth of them. I also checked heater temperature sensor and it looks ok.

 

[Kedzierski]

This problem is happening on my other work truck and it has no boxs at this time. Did not have chance to get to that stage yet.