Customer claims that the vehilce will only start if plugged in no matter what the temp is - I have verified that it will not start now - engine is full of oil - there is one CMDTC P0640 - intake manifold air heater ckt fault - ICP - RPM - IPR - Fuel PW -all look good - fuel looks good - glow plug relay is working and 7 of the 8 glow plugs ohm out good - 50 degrees here today - any ideas would be greatly appreciated