my 4hi light is always on even when im in 2hi, why?

 

Did you check the encoder on the transfer case itself? Sometimes it will break and won't show it as being in a different setting. My 98 did that, couldn't figure out why it was always showing 4hi.

 

no i have not. can you tell me where exactly its located? or show a picture of what it looks like? this way i can check it. thanks so much

 

The reason the light is staying on is because the front axle is not disengaging properly and the light is activated by a fairly simple switch in the front axle next to where the engagement cable enters. Your problem is most likely a failed vacuum switch located on the transfer case or, just as likely, a sticking front axle engagement cable.

The vacuum switch is located above the front driveshaft output most easily accessible from the back side of the t-case. This is a very common failure point. You will know that it is failed if you have vacuum to the front axle engagement diaphragm with the engine running and the 4wd system in 2HI.

If, after disconnecting the vacuum lines from the switch, you are greeted with transmission fluid, you have another problem along with the failed switch; a failed transfer case input seal which requires the transfer case be dropped to replace the offending seal.

The front axle engagement cable should move 1/2" to 3/4" when vacuum is applied to the vacuum diaphragm and move back when vacuum is no longer applied. If disconnected from the front axle, it should move back and forth fairly freely.

 

thanks, and this applies to my truck that has the manual 4x4 shifter on the floor that you pull by hand right? and one other thing that im curious about, do i have a separate computer for the 4x4 or body?

 

Yes, this applies to both the manual and older push button systems.

No your year does not have another computer for the body not one for the 4wd given that it is a manual shift t-case.

 

i see the switch on the t case. but i pulled the vacuum line off near the vacuum pod under the battery because it was easier to do. and sure enough there was vauum there even though im in 2hi. then i went to see if the light was off and now it was. can i leave the line disconnected and capped until i get the switch? also there is 3 prongs on the t case switch, can the lines be plugged anywhere on the switch? or do they have to go back on the same prong? also shoulg i get a GM switch or a dorman aftermarket? and what kind of oil is in the t case? i see a small leak near the back near the tail shaft...