Transmission sensor malfunction

[entrapment505]

I have a 2002 duramax with 86000miles It resently started to not display which gear I was in. for example no light box around the D in drive. Now My check eningie light came on. I hooked up the obd2 and a TRANSMISSION SENSOR MALFUNTION code and a TRANSMISSION HIGH OUT PUT code came up. When just the gear light was going in and out i thought it may be a short in a wire harness or connection but now I am not sure any help would be great! Tony

[Luis]

I'm no expert, but search NSBU switch. You can replace it your self and $ave some money. Its on the outside of the tranny and step by step instructions can be found on this site. Good luck & welcome...Luis

[david12]

common problem with early allison replace module on side of tranny be sure it is updated version. the early ones get moisture in them.