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Home >> Buick >> 2016 >> Envision >> Repair and Diagnosis >> External Pages >> Different car >> Section 180 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> DTC B2455: Cellular Phone Microphone >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2016 Buick LaCrosse. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B24 Cellular Phone Microphone. It may take up to 2 min for all vehicle systems to power down.
  2. Test for 250-850 Ω between the microphone low reference circuit terminal A and ground.
    • If less than 250 Ω 
    1. Ignition OFF disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module.
    2. Test for infinite resistance between low reference circuit terminal A and ground.
      • If less than infinite resistance repair the short to ground in the circuit.
      • If infinite resistance replace the K73 Telematics Communication Interface Control Module.
      • If greater than 850 Ω 
    1. Ignition OFF disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module, ignition ON.
    2. Test for less than 1 V between the microphone low reference circuit and ground.
      • If greater than 1 V, repair the short to voltage on the circuit.
      • If less than 1 V
    3. Ignition OFF, test for less than 2 Ω in the microphone low reference circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the vehicle K73 Telematics Communication Interface Control Module.
    • If between 250-850 Ω 
  3. Ignition ON test for 8-10.5 V between the microphone signal circuit terminal B and ground.
    • If less than 8 V 
    1. Ignition OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module.
    2. Test for infinite resistance between the microphone signal circuit and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • If infinite resistance
    3. Test for less than 2 Ω in the microphone signal circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • If less than 2 Ω, replace the vehicle K73 Telematics Communication Interface Control Module.
    • If greater than 10.5 V 
    1. Ignition OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module, ignition ON.
    2. Test for less than 1 V between the microphone signal circuit and ground.
      • If 1 V or greater, repair the short to voltage on the circuit.
      • If less than 1 V, replace the K73 Telematics Communication Interface Control Module.
    • If between 8-10.5 V 
  4. Test or replace the B24 Cellular Phone Microphone.
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