Hi , my 2003 Cummins truck won't start when it gets cold , I checked the power at the heating grid with a test light , and there is no power there when the wait to start light is on ? where does this feed from ? I checked the the junction box and there is no listing for this ?

 

How cold is it there? The heater grids will not come on unless it is colder than 55*F. The indicator light will come on every time you turn the key on, tho.

 

I have been watching videos of Cummins starting at 20 below... you could have injector problems or ring problems.

The grid heater relay is controlled by the ECM. The relay is over by the passenger side battery, you should see the cables running to it from the batteries and to the heater around the front of the head.

If you need more info, let me know.

 

well it has been frosty mornings , so it sould be cold enough , what are the symptoms for injectors ? it does not smoke ? but it is lazy ? fuel pressure is good , and the rail pressure's are in range ?

 

Hard start when cold, white smoke on start up.

It could also be your rail pressure sensor.

My advice: Start with the cheapest stuff first.

Do you have any codes?

When you say the rail pressure is in range, do you mean that when you are cranking it, or when it is running?

What is it doing, exactly?

 

well , when it gets colder out it won't start . plug the block heater in and it will , good all day , it just cranks over next morning , fuel pressure is 10 psi , rail is 6000 to 8000 when cranking ,

 

Injectors is my best guess based on every 03 that has the same no start if not plugged in problem, but will start if plugged in.

 

Hey guys my first time to reply to this forum. brand new member hope iam doing this right. I also have a 2003 3500 with the same problem. Just started this winter with the cold start problem. if i cycle the key about 5 times it will start, but has to crank for a while. hope this will help the guy with the same problem. also I have done the lift pump volume check and made sure the intake grid heaters are working. I have come to the conclusion that if you have the original inj. pump and injectors its time to replace both