Had to use 4WD for the first time this winter. I have the manual t-case. So i get it into 4-hi but the 4WD light does not come on in the dash. I tried 4-lo and get the same result. So i checked for codes in the instrument cluster and found OD, A7, AA

0D - PRNDL switch input circuit open
A7 - VIN checksum error
AA - PCM messages not received

I do have the Smarty Loaded, Is this a problem caused by the Smarty ? During the light and gauge test the only lights not to light up were the SERV 4WD lights.

 

Took smarty off the truck and still get no light. I checked the connector on the top of the t-case and it looks good. May have to bow down to the dealer.