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 receives no valid vehicle speed data from the TCM for more than 1 second.

DTC P1504 is a Type A DTC.

DTC P1504 is a Type A DTC.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Engine running, observe the DTC information with a scan tool. DTC P1504 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

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

⇒	If no communication with the TCM, refer to Symptoms - Data Communications for further diagnosis.

2. Ignition OFF, disconnect the harness connector at the TCM.
3. Ignition ON, test for 1.5-3.4 volts between the CAN serial data low circuit terminal A7 and the CAN serial data high circuit terminal A17.

⇒	If not within the specified range, test the CAN communication circuits between the ECM and the TCM for an open, short to ground, or a short to voltage.

⇒	If the circuit tests normal, replace the ECM.

4. If the circuits test normal, replace the TCM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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