Ok first off I was getting some grinding in the front right of the truck so I was sure the vacuum servo was toast. So I replaced it will a cable, and capped the vacuum line. Now the truck will go into 4low while in neutral like it is suppose to. Sometimes you have to press the switch twice to get it to go in, but it will never go into 4hi. Is this the encoder module? When I use to work at a dealership we had a new body style come in and it had 4hi and no 4low and that was the encoder module. I have the old body style with the push button 4wd switch. It is on the left hand side of the of the dash. With a green and orange light. Any help would be great.