Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P0864: TCM Communication Circuit PerformanceCircuit/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 once the above conditions are met. |
Conditions for Setting the DTC
The ECM receives no valid vehicle speed data from the TCM for greater than 4 seconds.
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
- 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.
Important: Record all Failure Records before clearing the DTC. Using Clear Info erases the Failure Records from the engine control module (ECM) and transmission control module (TCM).
| ⇒ | If any TCM Freeze Frame/Failure Records are recorded refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
| ⇒ | If DTC P0864 sets and no TCM DTCs are present, replace the ECM. |
| ⇒ | If DTC P0864 and TCM DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module replacement, setup, and programming
