This bulletin applies to 2015-2018 Cadillac Escalade vehicles equipped with a 6.2L engine. The SES lamp may be illuminated. DTCs P2635, U0074 and/or U18A2 may be set.
It may be found that actual fuel pressure (low pressure system) will be reading substantially higher than desired fuel pressure. The cause may be a loss of communication between the engine control module and the fuel pump control module.
Follow published diagnostics for any communication DTCs set (U0074 would take priority over U18A2 if both are set) before addressing DTC P2635. If P2635 is not resolved by correcting the communication DTCs, only then should service manual diagnostics be followed for P2635.
It has been found that a communication issue between the FPCM and ECM can potentially induce P2635 and result in pressure differential between actual and desired fuel system pressures.
If the actual fuel pressure is substantially higher than desired (by 10 psi or more), replacement of the fuel pump control module or fuel system components typically will not resolve the issue.
If the actual fuel pressure is substantially lower than desired (by 10 psi or more), GM recommends following service manual diagnostics.