GMC Troubleshooting Questions? Ask a Mechanic for Answers
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.GM has released a service bulletin dealing with the type of no crank problem you are having that may be related to the issues you are having. I have enclosed it in the link below for your review. Copy and paste the link to your browser to open and view it.https://dl.dropboxusercontent.com/u/104923897/No%20crank%20Jun%2010.pdf
If you connect your scanner to the system and read your data stream are you able to see the crank request?
Well unfortunately in order to be able to do the diagnostics properly you are going to need to find someone who has this and can help you do the testing.
Which wire and fuse are you running power to at the relay?
There are two fuse that power the starter relay one is the IGN fuse E located in the under hood fuse panel and the other one is the IGN fuse A also located in the under hood fuse panel. Are you sure one of them is not blown. See the wiring diagram in the link below for reference. Let me know which fuse your using to power the start relay. Copy and paste the link to your browser to open and view them.https://dl.dropboxusercontent.com/u/104923897/Start%20Jun%2013.pdf