My cousin just got his built 2006.5 5.9 out of the shop and ever since then when he plugs in his smarty ssr and It didnt down shifting right and nothing on the dash wash light up. And Couldn't see the PRND21 or the tow haul lights. Any ideas?

 

Turn the shift defuel back on. You don't nee dit turned off 99.9% of the time anyway.

 

Wont even turn over now.

 

Start checking wiring harnesses on the transmission. The dash gear indicator and neutral safety switch is controlled by the range selector where the nuetral safety switch used to be on older inuts. Shifting is influenced by the main trans harness.