I have an '06 silverado 1500 4WD with the 5.3 and roughly 78k on it. A bunch of codes popped up for the transmission. I am getting shift solenoid codes, clutch and torque converter codes. Im losing first gear and overdrive when these codes pop up or vice versa. The funny thing is when i put the truck in 4WD then back to 2WD the codes go away and the transmission shifts perfect for a day or so. The ATF isnt burnt and has good color.
This leads me to beleive I have an electrical problem causing these codes and the shift solenoids to malfunction. Ive asked around and im stumping all the mechanics I ask. I have had trouble finding a good diagnostic guy. Anyone want to weigh in?

 

Personally I wouldn't want to hazard a guess without seeing a wiring diagram first.
Then I'd check the power and ground circuits.

 

smd1982,

Has your concern been resolved? Feel free to contact me privately as well with the last eight of your VIN if you need additional assistance. Thank you in advance.

Tricia, GM Customer Service.

 

Thanks Tricia
Be sure to come back SMD1982 and let us know what you found out. We'd be interested in know what gremilins crawled into your truck

 

Still working on it.I will update when I can.