Lights Varying at Idle

[dPierce]

For the past few weeks I've noticed my the brightness of my lights varying considerably at idle, dash and overhead lights specifically. The idle bounces up and down slightly when the truck is cold and the lights follow?



Any ideas? Volt meter remains steady throughout.

 

[T Peterson]

Grid Heaters

Its just your grid heaters cycling.



Tom

 

[Tony T.]

Mine does the same, the voltmeter will drop to around 12 volts (giving the interment dimming of the panel lights) while the grid heaters are on then after about 2 to 2 1/2 minutes shut off, and voltmeter goes to 14. 2 volts. I don't know for sure may have something to do with grid heaters cycling putting such a load on the batteries. Maybe some one else that knows for sure will chime in.

 

[T Peterson]

The grid heaters draw alot of juice, thats why the alternator puts out something like 130 amps, I could be wrong on this but I don't think so. They will come on everytime you start the truck if the temp is below 57-58 degrees and will shut off after you get up to about 20 MPH.



Tom

 

[coobie]

Grid heaters

My lights do the same thing. Its the grid heaters !!! coobie, 2004 ram H. O.

 

[David Muench]

It's definitely the grid heater, my 03 does it and my 01. 5 did it as well. The wipers move slower too when the grid heater is on.

 

[JThiessen]

On mine, even the heater fan pulses considerably. I Have been meaning to take it in to see what the problem is - but now that I know its the grid heaters, I'll wait till I've got additional work to be done before getting it checked.

 

[Lorenz]

not only are the grid heaters on and drawing power but the alternator doesn't come up until the heaters are done doing there thing. watch the volt meter, @12v untill the heaters turn off then the alternator comes up and your at 14. 2v. you can hear the alternator "click" on after 30sec-1min after a cold start