Why would my Low Range light flicker and illuminate at low rpms, and go off at higher rpms?

I can accelerate and the light turns off. Once I let off the gas or coast, it comes back on and flickers to some degree, if not staying illuminated entirely...

Go figure...

I've tried shifting in and out of 4x4, high and low, reverse, forward, etc etc...



98 F150
5spd 4x4
Stock everything....

 

Look at some other indicators.
Does the charge light come on, flicker or do anything unsusal?
Does 4H lamp flicker?
The 4x4 lamps receive their ground from the GEM module to light them.
If the charge circuit is solid then the GEM ground has some issue.
If other lamps are not solid then you have a charge system issue.
Good luck.

 

Nothing else flickers.
I have a check engine due to an other issue, a sixty dollar replacement this sunday....

All of the drivetrain "precautions" have been administered and checked... fluid levels, contacts.. etc etc...

 

Sounds like a bad ground?

 

If the only issue is the 4L lamp action and there are no other malfunctions then the GEM or the lead to the lamp has a problem.
Your call to either let it go or prove the problem to the GEM for replacment.
The ground comes from/through the GEM to light the lamp. Power is already suppled to the lamp waiting for the ground to appear..
It's not cheap.
Good luck.