Headlights, tail lights, and turn signals blink

[Lund1990]

I have a 2004 crew cab short box that when I start the headlights, tail lights, and blinkers all blink for a few minutes. Any idea what the cause is?

[Tractorman]

13 minutes ago, Lund1990 said:

blinkers all blink for a few minutes.

 

Define "blink" with more detail. 

 

If you are meaning that the lights dim and brighten in a cycling manner after a cold engine start, then this is normal.  What you are witnessing is the post-cycling of the intake manifold heaters until the truck is driven or the engine reaches a specific operating temperature.

 

When the intake manifold heaters are post-cycling with an idling engine, the current draw is greater than the alternator output when the heaters cycle to "on", consequently, the lights will dim.

 

- John

[Lund1990]

Not that.  I own 3 cummins I know about grid heaters.  They actually turn off and back on. Like 1 second each way. Does it for a few minutes them stops. 

[Tractorman]

Thanks for the clarification.  I should have figured out that you are familiar with these trucks, just reading your signature. 

 

My brother-in-law owns a 2003 truck and I recall that he had a control module that operated his headlights.  I looked on-line and found this

 

"In a 2002 – 2005 Dodge Ram, the Front Control Module (FCM) is responsible for managing and controlling various electrical components and systems in the vehicle. Its functions typically include: Exterior Lighting Control: The FCM manages the operation of the headlights, turn signals and other exterior lights."

 

I would start my trouble shooting in the this area since your symptoms involve multiple lighting circuits.

 

- John

[Lund1990]

Thank you. I didn't find much online either. I was just hoping someone had had this happen before. Seems like it would be something a vehicle would do for the security, but i have a black key for truck. 

[Tractorman]

59 minutes ago, Lund1990 said:

Seems like it would be something a vehicle would do for the security, but i have a black key for truck

 

Didn't think abut that part - you may be on to something.

 

- John