[DDMAX2500HD]

I've got a good one so the silverado 05 2500hd duromax won't run with the ficm bolts connected to bracket however when I remove the bolts it runs but it's in limp home mode where it won't go over 40 or 50 miles an hour and cuts out under acceleration. When I push on the ficm unit while the truck is running it will die. Any help would be appreciated,if the ficm edu unit was bad the truck wouldn't run at all i figure but I'm a new Duramax owner so I'm still getting familiar with the vehicle

 

[DDMAX2500HD]

So I did an experiment and when I have the ficm mounted as it should with the insulators and vibration washers and bolted down it won't start, when I remove the bolts and the bottom corner of ficm makes contact with the mating surface of the ficm bracket it runs but poorly so now I'm thinking it's a grounding issue or wire short cuz it only seems to run when the ficm unit is touching the metal of the bracket and I thought that's why the insulator and rubber vibration washers were there for,The wiring harness looks wrapped up nicely by the alternator so i haven't looked for harness wire rub yet but thats probably happening tomorrow just to be sure,Does Anyone know the grounding points for the ficm unit or had this problembefore? hmmmmm

 

[DDMAX2500HD]

Then something in the ficm is shorting to the case.

I ran a groundwire from ficm case bolt to a ground bolt and its running better but still throwing out a dtc u1500 which is network serial bus(communication wire) plus an abs module and hvac module, Today i ran a engine to frame ground and cleaned some other grounding points,So you think the ficm is toast? From the other posts I read though the ficm is All or nothing either it runs or doesn't run it all