Service Information

Captiva

DTC B2455

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.

DTC Descriptor

DTC B2455 00: Mobile Phone Microphone Circuit

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Mobile Microphone Signal	B2455 00	B2455 00	B2455 00	-
Mobile Microphone Low Reference	-	B2455 00	1	--
1. OnStar Microphone Inoperative - Caller Cannot Be Heard

The mobile telephone control module provides the cellular microphone with a supplied voltage on the cellular microphone signal circuit. When the microphone is in use, voice data from the user is sent back to the mobile telephone control module on the signal circuit. The mobile telephone control module provides a ground for the microphone via the low reference wire.

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.

•	All the above conditions are present for greater than 10 seconds.

Conditions for Setting the DTC

•	The mobile telephone control module detects an open, short to ground or short to voltage in the cellular microphone signal circuit for 10 seconds or greater.

•	The mobile telephone control module detects an open/high resistance in the low reference wire circuit for 10 seconds or greater.

Action Taken When the DTC Sets

•	The mobile telephone control module 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.

Reference Information

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 Testing

Ignition OFF, disconnect the harness connector at the B24 mobile microphone.
Test for less than 10 Ω between the low reference circuit terminal 2 and ground.

⇒	If greater than the specified range, test the circuit for an open/high resistance.

Ignition ON, test for 9.5-10.5 V between the signal circuit terminal 3 and ground.

⇒	If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K82 mobile telephone control module.

⇒	If greater than the specified range, test the circuit for a short to voltage. If the circuit tests normal, replace the K82 mobile telephone control module.

If all circuits test normal, replace the B24 mobile microphone.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Mobile Telephone Microphone Replacement

•	Control Module References for mobile telephone control module replacement, setup, and programming