GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 CTS 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 OnStar Microphone Malfuncation

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 provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Cellular Microphone Signal

B2455 02

B2455 04

B2455 01

-

Circuit/System Description

Without RPO UAV

The communication interface module (CIM) uses the cellular phone microphone to allow driver communication with OnStar.

With RPO UAV

The communication interface module (CIM) and navigation radio use the cellular phone microphone to allow driver communication with OnStar, as well as to operate the voice recognition/voice guidance feature of the navigation radio.

Reference Information

Schematic Reference

OnStar Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

OnStar Description and Operation

Electrical Information Reference

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

Circuit/System Testing

Without RPO UAV

  1. Ignition OFF, disconnect the harness connector at the cellular microphone.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal A and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the CIM.
  3. Ignition ON, test for 9-11 volts between the signal circuit terminal B and ground.
    4. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the CIM.
    ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CIM.
  4. If all circuits test normal, replace the cellular microphone.

With RPO UAV

  1. Ignition OFF, disconnect the X4 harness connector at the navigation radio and the harness connector at the cellular microphone.
  2. Ignition OFF, test for less than 5 ohms between the low reference circuit terminal A and ground.
    3. ⇒If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the CIM.
  3. Ignition ON, test for 9-11 volts between the signal circuit terminal B and ground.
    4. ⇒If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the CIM.
    ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CIM.
  4. If all circuits test normal, replace the cellular microphone.
  5. Connect the X4 harness connector at the navigation radio. Verify DTC B2455 is not set as current in the navigation radio.
    6. ⇒If DTC B2455 is set as current, replace the navigation radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Mobile Telephone Microphone Replacement
    •  Control Module References for CIM or navigation radio replacement, setup, and programming