That is the heater grid coil light.

 

The coldest my truck has been in without being plugged in was -15 and it did ok. The other times I had it on and it seemed a little better.

 

Cummins dealers have them here for $18 if you want it right way. Otherside I'm told Dodge wants $55 for one.

 

03 cr came with a cord 04's didn't come with a cord

when you plug your bliock heater wait a few seconds and you will hear it lite up you will hear a sizzeling sound.

 

Yeah I knew that the squiggle line was for the heater grid, I have just noticed it has never been on anytime I have the truck plugged in so it is my gauge that it is workin. But cold for us here in Az are in the teens so you guys in the singles or negatives probably still get the light !!

 

I get the light almost every day..... Usually in the negative double digits here. I plug it in when it gets around -25F

 

how long does the heating element last, (plug)
how often do you replace them

 

idk about the cr's but on my 12v i used the cord off a john deere tractor.