Engine light flashes when put in 4wd

Is the truck engageing and running in 4x4 ok?Just light?

Yea it engages just the light starts to flash when moving

This is more than likely a bad shift sensor switch that controls the light to the 4x4 light all so,it is built in to the transfer switch, it self,the engine light may be totaly different issue,just being triggered by it,have you had the code,s pulled from engine light?

Ya it was for a evap but gunna scan it again in the morning. i wonder if it's the cats cuz I put it in 4 low and it revs higher and I no the cat need replacing