I have a 2001 ford f250 four wheel drive works but
only when light come on.switch on dash..locking
hubs work..when light comes on it works.when
light does not come on she will not go in to four
You have an intermittent problem. When the light is on that indicates that everything worked and when its not on it's indicating a problem. The most common problem is the shift motor on the back of the transfer case not shifting and sending feedback to the control that turns on the 4wd lamp. Like a starter motor you can lightly tap on the motor with a small hammer to free it up. If this trick works then you will need a shift motor as the contacts aren't able to move the current needed to function.
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