Can't Connect to J1850VPW P59 PCM
I have searched and searched and have not found a solution to my issue. I have been working at it for weeks now and am still pulling my hair out so I am seeking help here. I plan on contacting HP Tuners tomorrow to see if they can help as well.
I will give the back story and try to keep it as short as possible.
I have a 2004 GMC Sierra 1500 that I am trying to get tuned. A reputable tuner in my area has tuned the truck twice before, first time for cam install and second time for electric fans and 6 speed swap, with no issues. This time around I have boosted the truck and installed all the supporting bits like fuel system etc. When I arrived to his shop he could not connect to the PCM through the obd port, spent three hours trying to find solutions and did not find anything. I have tore the truck apart to try and find the issue, I have checked every module, they are all performing correctly I even bought an oscilloscope to test these and everything is all good. I also tried isolating just the pcm at the SP 205 splice pack to rule out all of those other systems causing issues and still no luck. My tuner is able to flash a base tune onto the PCM no problem on his bench harness, so he told me the ECU was more than likely not the problem but I bought another ecu anyway, flashed the base tune on it and still no luck.
Before I started tracing all individual grounds my buddy recommend I go to the junk yard to get parts to make a bench harness, so I did that today. From our research we should be able to make this bench harness connect to VCM Scanner or VCM Editor and at least identify the computer, vin, operating system, etc. I also bought another PCM at the junkyard today so I could test it as well since it had never been flashed (to my knowledge). All three PCM's were UNABLE to connect on any VCM suite product with the bench harness. Which would rule out any interference or issues from the truck side causing the issue.
From our testing the only thing I can conclude is that either the MPVI2 dongle we are using is not working correctly (however we have been able to connect to every single other vehicle we have tried, although all of those are can bus systems), or there is some sort of software issue going on with my vcm suite products. We have tried the standard and the beta versions. And I also find the dongle hard to believe since my tuner has a MPVI3 and seemed to have the same exact problem.
So is there an issue with the current VCM Suite products connecting to J1850VPW data links? Specifically in P59 PCM applications?
PLEASE HELP
