I have 04 f150. The 4 hi works and the light shows its engaged but the 4 low and 4 low light does not engage.

 

When you try to put it in 4L are you parked and have it either in neutral or park? If ya parked and put it in 4L it will take a few moments to engage. If your doing that and it's still not engaging I would say something is wrong with your transfer case more the likely, but I can't guarantee anything

 

Are you coming to a complete stop and shifting into "N" before trinig to select 4X4 Lo ?

 

LOL...we must of been typeing at the same time...

 

Hahahaha, I was just about to say the exact same thing I reckon we both got good timing eh?

 

yes, i tried every thing its something mechanical

 

I'm not the best mechanic as your gonna be able to tell in this post but check all your cables and links leading from your transfer case, one may of popped loose. To do that all ya gotta do is pop your hood and just follow all your cables making sure their nice and snug, this is something ya can check while someone with more knowledge can tell ya the specific problem

 

If its going into 4 high, then its not the transfercase. Its a switch problem.

 

I just had to get my switch replaced. It would engage, but no light on cluster when 4h. have switch checked. good luck