DTC P1605: A/T Diagnostic Communication Line: Description
WARNING: This page is about a different car, the 2002 Nissan Pathfinder and 2002 Infiniti QX4. However, it is still accessible from the selected car via links, so may be relevant.
Malfunction information related to A/T is transferred through circuit from Transmission Control Module (TCM) to ECM. When testing DTCs related to A/T be sure to erase DTCs from TCM and ECM after repairs are made.