Trouble Code: U1899
Starter/Generator Control Module (SGCM) Lost Communication With Powertrain Control Module (PCM)
For DTC U1892, ensure all power and ground circuits to the electric-hydraulic power steering (EHPS) module including the motor are tested. A loss of voltage or ground to the EHPS hydraulic motor as well as to the module may cause a loss of communication.
DTCs U1883 and U1884 can be set inadvertently, when braking during the trailer towing. If only these codes are set as history only, clear the codes.
An intermittent open between a module and a star connector may cause this DTC to set.
An intermittent open on high speed GMLAN may cause this DTC to set.
An open voltage or ground circuit to a module may cause this DTC to set.
An internal module malfunction may cause this DTC to set.