4X4 works, but engaged after park

[yahthis1]

Hello,

I did the search but not much info.

My 4x4 act up today. After changing the timing belt, all the fluid front and rear differential and transfer case. Today I want to see how my 4x4 work. When I hit 4x4 HI drive fine and all 4 wheels drive the way is should, but I when I park the turn off the ignition, the front is engage every loud when the 4x4 still on. I test drive again 4x4 work fine drives 4 wheel, then park turn off nothing happen.

It only happens one every time when I turn the 4x4 HI "If I leave the 4x4 on all the time then nothing happen". I think it the vacuum, but don't know where is located. Can some one help? Thanks

 

[fourwd1]

You mention vacuum, does your truck have ADD?

 

[yahthis1]

I don't know. I brought to the shop the mechanic has no idea. He checked the oil level for all front, rear and transfer case. They are all good and new.

 

[SKIDPLATE]

Recheck everything you did previously.

If you changed the timing belt, check closely around that area. If it worked fine before, then you probably disconnected something or pulled something loose. The "add" is attached to your front left (drivers side) axle just off of the differential. It's part of the axle housing and does have vacuum lines attached to it. But don't stop there. Look around where you did any work. The problem is most likely there somewhere. Assume nothing.