Okay I will preface this by saying this is a truck I was given to diag at the shop. It was a trade in and it came in running. During the clean up process some one of the bright individuals in that dept tried using the superchips to do something to it and fried the ecm.
Thats where I got it. No run, no crank at all. I did not have any communication with ecm. Powers and grounds all checked out. I replaced the ecm with a used job from ebay and programmed it to the truck and did the vats learn. I am now getting the u0105 code (no comm with ficm) and p0090 (cp3 control cir). Basically the ecm is not grounding the EDU relay which supplies 4 powers to the ecm and the power to the ficm. Because the ecm is not grounding the edu relay I have no comm with the ficm. It is like the ecm is looking for something it is not finding and not grounding that circuit, yet the gm techline does not give us any indication of what its looking for. I tested a similar truck and it grounded the relay with key on so its not looking for oil or fuel pressure ect.
If I jump the relay the truck runs and starts fine. Any one ever run into this type of issue.
Thats where I got it. No run, no crank at all. I did not have any communication with ecm. Powers and grounds all checked out. I replaced the ecm with a used job from ebay and programmed it to the truck and did the vats learn. I am now getting the u0105 code (no comm with ficm) and p0090 (cp3 control cir). Basically the ecm is not grounding the EDU relay which supplies 4 powers to the ecm and the power to the ficm. Because the ecm is not grounding the edu relay I have no comm with the ficm. It is like the ecm is looking for something it is not finding and not grounding that circuit, yet the gm techline does not give us any indication of what its looking for. I tested a similar truck and it grounded the relay with key on so its not looking for oil or fuel pressure ect.
If I jump the relay the truck runs and starts fine. Any one ever run into this type of issue.
