6. If all circuits test normal, replace the HSM.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Driver or Passenger Seat Back Cushion Heater Replacement (Escalade with HP2) ()Driver or Passenger Seat Back Cushion Heater
Replacement (Tahoe with HP2) ()Driver or Passenger Seat Back Cushion Heater Replacement (without HP2) ()
* Control Module References (See: Testing and Inspection/Programming and Relearning) for the HSM replacement, setup, and programming
B2455
DTC B2455
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provide an overview of each diagnostic category.
DTC Descriptor
DTC B2455 04
- Cellular Phone Microphone Circuit Malfunction Open Circuit
Diagnostic Fault Information
Circuit/System Description
The communication interface module (CIM) provides the cellular phone microphone with a supplied voltage on the cellular phone microphone
signal circuit. When the microphone is in use, voice data from the user is sent back to the CIM on the signal circuit. The CIM provides a ground for
the microphone via the low reference circuit.
Conditions for Running the DTC
* The ignition must be in the RUN or ACC position.
* The system voltage is at least 9.5 V and no more than 15.5 V.
Conditions for Setting the DTC
* The CIM detects an open, short to ground or short to voltage in the cellular phone microphone signal circuit for 10 seconds or greater.
* The CIM detects an open/high resistance in the drain wire circuit for 10 seconds or greater.
Actions Taken When the DTC Sets
* The OnStar(R) status LED turns red.
* The CIM will not receive a signal from the microphone.
* Calls can be placed but the caller cannot be heard.
Conditions for Clearing the DTC
* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.
Schematic Reference
OnStar Schematics (See: Accessories and Optional Equipment/Diagrams/Electrical Diagrams/OnStar Schematics)
Connector End View Reference
