Diagnostic Instructions
DTC Descriptor
DTC P1601: Lost Communication with TCM.
Circuit/System Description
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.
Conditions for Running the DTC
• | The engine is running more than 2 seconds. |
• | The ignition 1 voltage is more than 11 volts. |
• | No output controls are active. |
Conditions for Setting the DTC
The ECM does not detect a valid message from the TCM.
Action Taken When the DTC Sets
DTC P1601 is a Type B DTC
Conditions for Clearing the DTC
DTC P1601 is a Type B DTC
Reference Information
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
Circuit/System Verification
- Engine running, observe the scan tool DTC information parameter. DTC P1601 should not set.
- 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.
Circuit/System Testing
- Ignition ON, attempt to establish communication with the TCM with a scan tool.
- Ignition OFF, disconnect the harness connector at the TCM.
- 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, replace the TCM. |
- Ignition OFF, test the CAN communication circuits between the ECM and the TCM for an open, short to ground, or a short to voltage.
- If the circuits test normal, replace the ECM.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine and transmission control module replacement, setup, and programming.