The controller area network (CAN) serial data bus is used by the engine control module (ECM) and automatic transmission control module (TCM) to share information. An example of information shared is engine speed, engine coolant temperature, manifold absolute pressure (MAP), throttle position and vehicle speed.

The ECM does not detect a valid message from the TCM.

DTC P1601 is a Type A DTC

DTC P1601 is a Type A DTC

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. Start the engine, observe the DTC information with a scan tool. DTC P1601 should not set.
2. If the vehicle passes the Circuit/System Verification Test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.

1. Ignition ON, attempt to establish communication with the TCM with a scan tool.

⇒	If no communication with the TCM, refer to Scan Tool Does Not Communicate with CAN Device for further diagnosis.

2. Ignition OFF, disconnect the harness connector of the TCM.
3. Ignition ON, verify that 1.5-3.4 volts is available between the CAN serial data low and the CAN serial data high circuits.

⇒	If the voltage is not within the specified range, replace the TCM.

4. Ignition OFF, test the CAN communication circuits between the ECM and the TCM for an open, short to ground, or a short to voltage.
5. If the circuits/connections test OK, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine and transmission control module replacement, setup, and programming