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 B DTC.

### Conditions for Clearing the DTC

DTC P1504 is a type B 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 DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.

2. Attempt to communicate with the TCM using 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 DTC information with a scan tool. Engine running, observe the scan tool DTC information parameter. Verify that 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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming