Circuit Description
The communication interface module (CIM) 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 CIM on the signal circuit. The CIM provides a ground for the microphone via the drain wire.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2455 Cellular Phone Microphone Circuit
Conditions for Running the DTC
| • | The ignition must be in the RUN or ACC position. |
| • | The system voltage is at least 9.5 volts and no more than 15.5 volts. |
| • | All the above conditions are present for greater than 10 seconds. |
Conditions for Setting the DTC
| • | The CIM detects an open, short to ground or short to voltage in the cellular 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. |
Action Taken When the DTC Sets
| • | The OnStar® 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 CIM detects the microphone connected for 5 consecutive 100 millisecond cycles. |
| • | A history DTC clears after 50 malfunction free ignition cycles. |
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Schematic Reference: OnStar Schematics Connector End View Reference: Cellular Communication Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the voltage measure within the the specified range? | 9.5 V- 10.5 V | Go to Step 4 | Go to Step 3 | |
3 | Test the cellular microphone signal circuit for an open or short to ground, or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 |
4 | Test the drain wire circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 5 |
5 | Inspect for poor connections at the harness connector of the cellular microphone and harness connector of the communication interface module (CIM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 |
6 | Inspect for poor connections at the harness connector of the CIM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 |
7 | Replace the cellular microphone. Refer to Mobile Telephone Microphone Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- |
8 | Replace the CIM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 9 | -- |
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
