red 454

a friends 2012 6lt v8 just went dead on him wont crank over or start

he had the DOD removed and had a cam + tune about six months ago all fine till now

it stopped on him the last week he reloaded the tune from his auto cal
and it must have cleared the code ,as it started OK
next morning it would not crank over just dead
it just keeps throwing the 2 codes PO651 and after you try to crank it will throw p2135
things we have tried
check all fuses
check battery voltage under load test
check voltage at starter ,under the bonnet at various positions
clean all the earth straps
charged the Bat over night all voltages show 12.5 to 13 v
remove and spray TB connector
if you remove the relay CRANK -R12 and bridge it out ,it will crank over and start and run in limp mode for a few min then stop (way does it crank over when i do this ) ?i HAVE REPLACED THE RELAY
i know the code PO651 is 5v circuit 2 ( no idea what that means though )
and code p2135 is TB correlation i'm assuming its saying the TB is not opening and closing ?
as when its switched on and i work the gas pedal you cant hear the TB opening and closing
any ideas on the constant PO651 code ( my guess its a sensor gone down or a short in the harness OR ecu is shorting out ,but which one or were is my problem ) no mater how much you try to clear it even disconect the Bat for a while then try to clear it
i'm no auto electrician so go easy
no acess to a tech2 support at the moment
cheers


ps I READ THIS on fix yar
Hi and welcome to FixYa, I am Kelly.

Here is the Description of the Chevrolet P0651 code: (Reference 2 circuit out of tolerence)
P0651 CHEVROLET Description Circuit Description
The powertrain control module (PCM) provides 5 volts to the following sensors:
The air conditioning (A/C) pressure sensor
The fuel tank pressure (FTP) sensor, if equipped
These 5-volt reference circuits are independent of each other outside the PCM, but are bussed together inside the PCM. Therefore a circuit condition on one sensor 5-volt reference circuit may affect the other sensor 5-volt reference circuits. The PCM monitors the voltage on the 5-volt reference circuit. If the PCM detects that the voltage is out of tolerance, DTC P0651 sets. Possible causes - Shorted sensor AC pressure Sensor or Fuel Tank Pressure Sensor
- Shorted sensor circuit (wiring to AC pressure Sensor or Fuel tank Pressure Sensor)
- Failed ECM Most likely there is a short somewhere... that is grounding out the 5V reference Voltage. This will take some serious work with a meter to determine where the ground has manifested itself. I woul;d start with the AC sensor and then check the fuel pressure sensor & wiring. This code will reset itself after 3 successful key strokes and there is no longer a short / loss of 5 V reference 2 voltage. Thaks for choosing FixYa, Kelly


so if the ecu was frukked way would it start with the relay crank R-12 removed and bridged out ?
hase thise car got a fuel tank presure sensore ?