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Home >> Buick >> 2017 >> LaCrosse Base >> Repair and Diagnosis >> Accessories & Equipment >> Entertainment Systems >> 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

  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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