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Home >> Cadillac >> 2007 >> Escalade EXT >> Repair and Diagnosis >> External Pages >> Different car >> Section 351 (Cellular Communication System) >> Diagnostic Information and Procedures >> DTC B2455: Cellular Phone Microphone Circuit >> Test Description
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Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The number below refers to the step number on the diagnostic table.

  1. 2:  This step checks that the VCIM is sending out the proper supply voltage.
DTC B2455

Step Action Value(s) Yes No
Schematic Reference: OnStar Schematics 
Connector End View Reference: Cellular Communication Connector End Views 
1 Did you perform the Cellular Communications Diagnostic System Check? - Go to Step 2  Go to Diagnostic System Check - Cellular Communication 
2 
  1. Turn OFF the ignition.
  2. Disconnect the cellular microphone connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Measure the voltage from the cellular microphone signal circuit to a good ground.
Does the voltage measure greater than the specified value?		 9 V Go to Step 3  Go to Step 4 
3 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 10  Go to Step 5 
4 Test the cellular microphone signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 7 
5 Test the cellular microphone signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 6 
6 Inspect for poor connections at the harness connector of the cellular microphone. Refer toTesting for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 10  Go to Step 8 
7 Inspect for poor connections at the harness connector of the vehicle communication interface module (VCIM). 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 10  Go to Step 9 
8 Replace the cellular microphone. Refer to OnStar Microphone Replacement .
Did you complete the replacement?		 - Go to Step 10  -
9
IMPORTANT: Perform the OnStar® setup procedure.
Replace the VCIM. Refer to Communication Interface Module Replacement .Did you complete the replacement?		 - Go to Step 10  -
10
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 2  System OK
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