I have a 2016 fx4 5.0. About a year ago I installed a Ridgid light bar. With wireless fob remote for on/ off/ strobe. No physical switch. Installed. All functions with the fob that came with the wireless box. Its wired to the battery with relay and inline fuse. Has been flawless since installed over a year ago. All of a sudden today the light bar is turning on when I start the truck. It is not wired into any of the trucks lighting. What the heck could be causing this.

 

I can tell you why but not where it's coming from.
The Light's Receiver is getting a signal from some source on the truck.
May be ignition leakage.
High voltage spark generates RF power that can radiate.
Your Fob generates a signal to turn your light bar on and off the same way.
If the light bar has batteries, they may be going dead or an intermittent relay contact.

 

Thanks for reply. Where should I start to try and fix this. If I can. This is what I have installed.

 

Most likely things: battery in remote is going out, the remote button is stuck in the "pressed" position, the wire harness relay is stuck on.

 

Came out this morning. For work. All was well. Truck started without light bar turning on. Remote works as it should. Ill have to keep an eye on it. For awhile. Thanks for the help.