After I start my 2003 Ram with the Cummins the dash lights, heater fan, and headlights if on, all dim for a few seconds then come back up then dim again several times. I can hear something around the firewall click on and off when this happens. I have only owned this truck a few months and not sure if this is normal. I thought it may be only when it is cold but I have noticed it after it is at running tempature.

2003 Dodge 2500 SLT Cummins

 

Should be only when it's cold due to grid heaters cycling on and off. The cycle runs a couple minutes, it should turn off if the truck hits 18mph before the cycle is over.

 

mine keeps doing that at over 18mph. it isnt speed dependent, it is more of time dependent.

it is perfectly normal. the altenator is not being used at the time, the batteries are running everything untill the grid heater turns off, then the altenator kicks on to recharge the batteries and run the rest of the truck. if you watch your volt meter you will notice it reading about 12 volts, then when the altenator starts working when the grid heater kicks off it will jump to 15-16 volts.

 

It cycles as long as it needs to achieve the target temp. Varies with outside air temp.
Bekim
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Thanks for the info, I was hoping thats what it was.
Great Forum and fast replies. Thank you.

 

I only mentioned the speed thing because I read in my owners manual (I know, weird that someone would read that) that it would shut-off if the truck hit 18mph before the cycle was complete. May not apply to newer trucks.

 

[sm=yikesomg.gif]

you read the owners manual!!!

[sm=partyparty.gif]

I'll confess, monday I thumbed through it trying to find the capacity of my NV5600

 

While we're on the Manual thing, It says to have the bands in the tranny adjusted when you change the fluid (at 48,000 miles), does that really need to be done or just an excuse for you to get it in the shop.