I have a 2003 2500 Dodge Diesel, 24 valve 5.9Lt. When the temperature drops below 70 degrees I have to plug the cord off the truck to keep it warm inorder to start. If it is not plugged in when the temperature is below 70 degrees it will absolutely not start. Could it be the heater intake relay.

 

Doubt it, I would think the common rail trucks would start better than our older ones without heat.

Mine has fired at almost 0 without heaters.

 

Welcome to DTR. If your heater grid relays are bad, it wouldn't make a difference at 70*, or even 30* for that matter. Most folks with these symptoms either have older batteries, bad connections or injector leaks. Are these the original batteries? If so, they have served you a very long time.
Back to morning brew. . .

 

The batteries and the connections have been replaced.

 

How's your lift pump slash pre-injector pump fuel pressure? Or maybe even consider an air leak in the fuel system maybe????

 

I live in upstate NY. Temps in winter get down below 0,
I took my grid heater out years ago, Truck has never
refused to start.

 

i had the same problem, and it was the contacts and the plunger on my starter. if your going to rebuild it i would just to it all in one setting. i just ordered the parts and replacing my brushes tonight.... this will be the third time ive had the started pulled down. i could do it blind folded by now.

well heres the link

https://www.dieseltruckresource.com/...ilding+starter


good luck, you should be able to find a local shop that rebuilds starters and alternators... thats where i ordered my parts from.

 

well i guess im just **** lucky, i have 711,000 on my truck and im still on the original starter, now i am on my 3rd alt, ans 2nd set of batteries....so i guess im just really lucky.

 

do you shut it off between trips???

 

There's an ambient air temp sensor in your intake tube, close to the air filter box, maybe faulty.

 

well yea even though the miles dont show it, but i guess i just do all my service to it to keep it in tip top shape, so it dont spin but a short second and fires right up