GM Service Manual Online
For 1990-2009 cars only

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 B1240 00: CD Mechanism Malfunction

Circuit/System Description

The radio monitors the CD mechanism for any errors or malfunctions during operation.

Conditions for Running the DTC

This test runs continuously.

Conditions for Setting the DTC

A malfunction is detected in the CD mechnaism.

Action Taken When the DTC Sets

CD operation will be disabled.

Conditions for Clearing the DTC

The DTC will clear when a CD mechanism malfunction is no longer detected.

Reference Information

Schematic Reference

Radio/Audio System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Ignition ON, verify DTC B1240 is not set.

If the DTC is set, replace the radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio replacement, programming, and setup