99 factory locker works but light flashes

[NasaE30]

I can hear the locker click in and it works normally but the light on the dash flashes constantly. It didn't do this before so I know its not normal? Any ideas fixes?

 

[GHARP57]

Are you in 4-lo?

 

[Yotaoffroad27]

Are you 100% sure the diff lock is actually working?

 

[TheDurk]

The prime suspect for this would be the diff lock detection switch on the rear diff or its wiring.

 

[IBallEngineer]

The prime suspect for this would be the diff lock detection switch on the rear diff or its wiring.

The usual suspects?