I have a 98 F150 5.4l with electronic 4wd but when I go to turn it on the light doesnt come on and it doesnt engage.

 

Had same problem with mine nothing would happen. Turned out to be a bad transfer case shift motor. Changed it out and works fine now.

 

Is that costly?

 

there are also resistors in the dash that go out. knock on wood i haven't had to deal with this yet..

 

Try rapping the motor with a small hammer they do stick . Worked on mine

 

do you hear the dash clicking? if not resistors, or switch. If it does click its your t-case motor. If his dash light isn't coming on it has to be an electrical issue, not mechanical.

 

Yeah it clicks but not everytime

 

try swapping your switch first if it doesn't always click.

 

what is that switch called?

 

the 4x4 selector switch. its electronic right?

 

yes

 

Mine was doing same as yours is doing. It is not clicking in the dash because it is not completing the circuit between switch and motor. Mind would work for a minute then kick out of 4wd. Then it finally just stuck in 4wd. Troubleshoot it and mine turned out to be t-case shift motor.