2016 GMC Savanna with no power getting to any OEM modules

[Scott LaBonte]

HELP!!!

 

First, thanks for any help you may be able to provide. I currently have a 2016 Savanna sitting at a dealership with a very frustrated mechanic. This Savanna is a cutaway model with a type III ambulance box on back. We have had no electrical problems with this vehicle before. On one particular morning my personnel had returned back to the station after completing a 8 hr patient transfer - NO issues during this time. 3 hours later we tried to start the vehicle to move it and had no crank, no start.. not even a click... Had the vehicle towed to our nearest dealership. The dealership first replaced the main fuse block because of no power coming out of the block, there is power coming out of the fuse block now after replacement with a new one. Same symptoms persist. When connecting a computer to the vehicle, none of the OEM control modules appear to have power.... What are we missing? According to the ambulance mod company, they do not cut into the ignition anywhere, just monitor OEM systems. 

 

What are we missing???

 

Any and all help appreciated!!!! We really need to get this ambulance running and back on the road ASAP... I've done many google searches with no success.....

 

Thank you!!