Sir - not an expert by any means, but happy to try and help. If you're lookiing for answers do a google search and you'll find them on the site, and if not a forum should do ya: "site:yotatech.com search terms"...

If you don't have manual hubs, that means you probably have the ADD hubs. While nice, this system has a combo of vacuum and electrical components with numerous points for failure. I'd recommend getting a set of manual hubs (they'll increase your MPGs and decrease wear on your front axles). Buying a set of OEM Aisin's for/from your gen pickup is best (pick and pull/Toyota parts yard/ebay) and then you can rebuild them for $20 in new gasket plus some of your time... But if you can't locate and aren't doing heavy wheeling with super large tires, the new Warn's are good too.
Once you have your manual hubs, you can proceed w/ the ADD delete. 4x4 wire has a good writeup here: http://www.4x4wire.com/toyota/tech/add/

That *should* resolve your issue.

If lookign for a quick fix, try reversing and then pulling forward a couple times once you engage/turn on the 4wd. Sometimes that'll fix.

And if you're dead set on keeping the ADD, head over here and follow the FSM to troubleshoot: http://personal.utulsa.edu/~nathan-b...26addcontr.pdf

Good luck!

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I should clarify that the manual hubs aren't a necessity, but are a solid upgrade as they increase your MPGs and decrease wear on your front CVs as they no longer spin except when engaged for 4wd.