DTC P1504. Chevrolet Joy 2008

For 1990-2009 cars

### 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 P1504: Loss of communication with transmission control module (TCM).

### 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 communication network called the GM local area network (LAN). Two circuits are used to communicate LAN data between the ECM and TCM.

### Conditions for Running the DTC

The ignition is ON.

### Conditions for Setting the DTC

The ECM receives no valid vehicle speed data from the TCM.

### Action Taken When the DTC Sets

DTC P1504 is a type A DTC.

### Conditions for Clearing the DTC

DTC P1504 is a type A DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Testing

1. Ignition ON, observe the DTC information with a scan tool. Verify no DTCs are set

⇒ | If any other DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Attempt to communicate with the TCM with a scan tool.

⇒ | If the scan tool is unable to communicate with the TCM, test the communication circuits between the TCM and the ECM for an open/high resistance. If the circuits test normal, replace the TCM.

3. Clear the scan tool DTC information parameter. Engine running, observe the scan tool DTC information parameter. Verify DTC P1504 sets this ignition cycle.

⇒ | If DTC P1504 sets this ignition, test the communication circuits between the TCM and the ECM for an open/high resistance. If the circuits test normal, replace the ECM.

4. 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