P1640 - Powertrain DTCS Available In Another Module

P1640 - POWERTRAIN DTCS AVAILABLE IN ANOTHER MODULE

Description:	Vehicles using a secondary Engine Control Module can request that the Powertrain Control Module illuminate the Check Engine light when a failure occurs which affects emissions.
Possible Causes:	DTCs stored in a secondary module, which requested the MIL to be turned on.
Diagnostic Aids:	Call -up PID address 0946 to determine the secondary module requesting MIL illumination. Once the secondary module is determined, request the DTCs from the module.
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	-	-	See the appropriate INTRODUCTION - BI-FUEL article for instructions on how to retrieve DTCs from the secondary module. See P1640 Diagnostic Trouble Code (DTC) Descriptions for additional information.