longbed

NOw that it is getting colder i notice the light stays on longer.Went from 70 to 45 start temp now light stays on a long time. Are there any outside temp verses heater length times on an 03 cummins. Or whatever it is until light goes out before starting?

bigblock2stroke

Yes, I can't remember the exact table off the top of my head.

You should see 10 seconds at the 45 (I think its less than 50 more than 20).

If less than 20, its on for even longer (30 secs. I think?).

Its the intake air heaters heating up the air in the intake manifold for less smokey cold starts. The colder it is the more heat you need, the more amps you need to get that heat. Cold starts are why you have 2 batteries.