Lights surging

[obie1]

Has anyone noticed that after starting the engine (after the glow signal goes out) the truck appears to idle fine yet one can hear some sort of cycling going on? Cycling in the sense that the interior lights get brighter (door open) and then dim in sync with the audible cycling. Door closed; headlights on ; the interior cluster lights dim and brighten.







Outside Temperature 30 Degf

Heater/defroster and fan OFF

 

[Slow Six]

Just your grid heaters cycling until the engine is warmed up a little. This is normal abd all is working well.

 

[Gary - K7GLD]

YUP - normal in cooler weather for the first few minutes - been that way since the Cummins was first used in the Dodge trucks I guess...

 

[klenger]

The alternative being glow plugs.

 

[obie1]

I had failed to mention it happens also after the engine has warmed up. (About 70 miles) Say I stop at the store open the door interior lights come on. They surge then as well.

 

[lschultz]

Its normal. Outside temp is cold and the air intake sensor(don't remember if thats what they call it)senses the air temp. If you let it set long enough the fast idle will kick in. 30 here this morning and I stopped at store to get some breakfast tacos and left it running while I went in to get them and when I got back to truck idle speed had increased.

 

[obie1]

Thanks guys great replies and help.



Stay warm and keep the shiny side up

 

[Byershome]

I noticed the same thing on my truck and mentioned it to the dealer when I took it by for some other minor issues. I took a guess that it was do to the reasons given above... . they just looked at me with a dumb look and said I suppose it could be. Guess I better go somewhere else because these guys don't seem to have a clue.

 

[obie1]

JHByers that's why we all use this forum.



Like yourself I thought the reasons were as mentioned, but that re-assurance we get from fellow owners/mechanics/"bombers" helps us get that warm fuzzy feeling.



Most dealers/service guys have no clue, therefore I live by the rule



"An educated customer is a satisfied customer!"

 

[bmoeller]

Originally posted by obie1

"An educated customer is a satisfied customer!"

Assuming they're not mad after finding out they shouldn't have purchased their piece of crap because of all of the problems... Even then, some still don't figure it out.

 

[ceaman]

I have the same problem with the surging lights... even at 50º it happens... . even after running for 24 hours straight

 

[CLAYTON]

Mine will only surge for a couple of mins or until I drive past 18 mph... It's fine after that unless I turn off the truck. . even when it's warm. . when I turn it back on with a 3 sec wait to start it will cycle the grid heaters again. . and my understanding is that happens because of the out side temp is what triggers the cycling not the temp of the truck... Is that right?