I have an 01 manual duramax that I purchased not running supposedly because it was struck by lightning the first thing I changed was injector module located on passenger valve cover as I was told thats what was wrong witch got it to where I can start it but dies after 3 seconds everything in truck works but fuel gauge I filled the tank and gauge stays at empty I have trace most the wiring removing the covering and unplugin plugs checking for any burnt or melted wire with no luck ive plug in tech 2 and all that comes up is unable to connect with ecm so i installed a spare ecm from a parts truck witch is a 2002 chevy duramax allison automatic and have the same results I then took my ecm and installed it in a buddys 2002 chevy automatic duramax and plug in tech 2 same results cannot connect with ecm but his fuel gauge still work I have checked fuses/relays 6 times all good do I have 2 bad ecms? did my truck burn them up? and what would cause this ive tryed the vats relearn in hope that somehow the security system had locked me out of the computer but nothing changed anyone have any idea what to do next short of buying anothrr ecm to find out if my truck is burning them up any help or info would be much appreciated

 

is the vin normal in your tech 2 mine was hit and a no start and the ecm had a vin that looked like 1@)(*%&@61()*^!% replaced ecm and reflash the trucks vin in and it runs

 

I installed ecm in truck and hooked up tech 2 and could not locate vin my obd2 says cannot connect with ecm and idk why

 

sounds locked

 

how do I unlock it? without obd2

 

tonight I dropped fuel tank to inspect wiring to rear half of the truck and found nothing I also unhooked batterys and hookex them back up with charging system unhooked still only about 3 seconds of run time and dies but now my security light is on solid at all times unless key is onthen rotates through on messege screen but still no connection between obd2 and ecm but the security light is new not sure if im getting closer or further away

 

sounds like the ECM is locked beyond fixabilaty. I think you need a unlocked ECM program it to your truck the trucks correct vin and so on the sucuraty light on constant is theft deterrent system and I believe that's what's killing it

 

sounds like a bonkered ECM to me. these ECMs have been known to go into weird security mode shutdown and it seems the only way to clear it when all of the usual remedies fail is a new ECM.

before going through the expense of a new ECM, try going through the fuel system first. make sure there is no restrictions, kinks, etc in the rubber lines. filter is good and there is no air in the lines.

 

good point haha i didnt even think to tell him to check the fuel

 

Also check the fuse for the cigarette lighter. This also powers the obd port and if blown will prevent communication with the ecm