Diagnostic Instructions
DTC Descriptor
DTC P0864: TCM Communication Circuit Performance
Circuit/System Description
The transmission control module (TCM) sends vehicle speed data to the engine control module (ECM). The data is sent to the ECM through a high speed network called the GM control area network (CAN). Two circuits are used to communicate CAN data between
the ECM and TCM. A fault in the CAN will not cause DTC P0864 to set by itself. If a CAN fault occurs, other DTCs set before DTC P0864.
Conditions for Running the DTC
| • | The ignition is ON for greater than 3 seconds. |
| • | The ignition voltage is between 10-18 volts. |
| • | No other CAN errors are present. |
| • | DTC P0864 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM receives no valid vehicle speed data from the TCM for more than 1 second.
Action Taken When the DTC Sets
DTC P0864 is a Type A DTC.
Conditions for Clearing the DTC
DTC P0864 is a Type A DTC.
Reference Information
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Note: Record all Failure Records before clearing the DTC. Using Clear Info erases the Failure Records from the ECM and TCM.
- Ignition ON, record the DTC Freeze Frame/Failure Records.
- Clear the DTC information with a scan tool.
- Ignition OFF for at least 30 seconds.
- Engine idling for 1 minute. DTC P0864 should not set.
| ⇒ | If DTC P0864 sets and no TCM DTCs are present, replace the ECM. |
- 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.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module replacement, setup, and programming
