99 Silverado 4 wheel engagement

I have a crazy problem with the 4 wheel drive. Initally it would not enage at all replaced the dash switch and now it will switch in an our to auto, 2w, 4h and 4lo, but it wil only do it if the key is cycled. So if I start the truck in 2w it will not switch unless the truck is shut off and then 4h is selected. Has anyone had any similiar issues???? What was the fix? No codes at this point.

What transfer case?
How Have you checked for codes?

Will it switch from 4W to 2W without key off thing?

not sure on the t-case number. just a 1/2 ton ext cab 99 silv

There are no codes

No it will not switch with out key off/on routine

How and with what did you check for codes?

Does the 4W buttons have a auto 4W button.
The transfer case ID is on back of transfer case.

snap on scanner

yes it has auto, 4hi, 2hi and 4 lo. I will check the tag on the case.

If the snap on scanner is transfer case/transmission capable it should set a code if a problem.
Just OBD11 scanner will not get into transfer case stuff.
Did you read out all shift data and go threw the shift test built into scanner.

I have a crazy problem with the 4 wheel drive. Initally it would not enage at all replaced the dash switch and now it will switch in an our to auto, 2w, 4h and 4lo, but it wil only do it if the key is cycled. So if I start the truck in 2w it will not switch unless the truck is shut off and then 4h is selected. Has anyone had any similiar issues???? What was the fix? No codes at this point.

I would guess its the transfercase encoder motor...

with the drive train oem specific codes I can get you in the correct direction..

okay I will rescan and see if anything has come back up.