We're in a remote part of NY state and can't get an appointment with the nearest GM dealer for a few weeks. So, I decided to get a new glow plug and install it. I did, but wanted to reset the computer. I found a nifty bluetooth
device on eBay for $25 with shipping that connects wirelessly with my netbook in the truck and reads and resets the ECM codes.
I installed the software, connected to the bluetooth scanner and it worked like a charm - read the codes and had the option to clear them. In my case it was P0674 meaning glow plug #4.
Thought I would pass it along.