I would start by searching TSBs for this problem for your year truck. They have several TSBs for this problem and code for other year GM vehicles including trucks.
here is a link to a video covering the repair and below that is a link show just one of these TSBs
https://www.youtube.com/watch?v=D5JFju6Y694https://static.nhtsa.gov/odi/tsbs/2012/ ... 9-8347.pdfI used to use Alldata to obtain somewhat decent factory information and service procedures including TSBs and recalls yet I am unsure what they offer for your year truck. it is worth a look and a subscription if they cover your vehicle.
Just make sure to validate the data and procedures found on their site with common sense as I have found incorrect data carried over from the factory that was never corrected with a update or service bulletin procedural update. ( meaning no one caught the incorrect data or at least they never reported it to the factory ) Normally this type of incorrect data shows up in diagnostic flow charts where test a leads to either result x or y and they would have these reversed with a good mechanical background and willingness to not blindly follow these flow charts without it making sense will keep you out of trouble.
I will admit this type of incorrect data is rare but can lead you down the wrong and most of the time expensive rabbit hole.
Example while working at Mitsubishi diagnosing a crank but no start on a brand new never sold SUV a diagnostic flow chart lead me to either having a bad computer or bad relay feeding the computer the diagnostic flow chart along with my test results showed the computer was bad yet common sense showed the relay was bad since it was not feeding the computer power .
My gut is telling me the tsb above very well may apply to your problem. it certainly is worth looking into. perhaps other people here whom have solved this problem with your year vehicle will pipe in. for now I hope this gives you something to research and I hope this in some way helps solve your problem.
Posted: May 23 2020, 10:46pm