DTC P1698: No Bus Message From Trans Control Module: Description
WARNING: This page is about a different car, the 2000 Dodge Intrepid, 2000 Chrysler LHS, 2000 Chrysler Intrepid, 2000 Chrysler Concorde, and 2000 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.
Messages from Transmission Control Module (TCM) are monitored when engine is running, transaxle in Drive and battery voltage more than 10 volts. DTC will set in PCM memory if no bus messages are received from TCM for 10 seconds. Possible causes for DTC to set are: defective PCM, or defective connectors or wiring.