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Home >> GMC >> 2018 >> Terrain SL >> Repair and Diagnosis (Single Page) >> Accessories & Equipment >> Entertainment Systems >> Cellular System, Entertainment System, And Navigation System - Diagnostic Information And Procedures >> Diagnostic Information And Procedures >> DTC B2455: Cellular Phone Microphone Circuit (IO5/IO6/IOB) >> Circuit/System Testing
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Circuit/System Testing

  1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the B24 cellular phone microphone, Ignition ON/Vehicle in Service Mode.
  2. Test for 8.0-10.5 V between the signal circuit terminal B and ground.
    • If less than 8.0 V 
    1. Ignition OFF/Vehicle OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module.
    2. Test for infinite resistance between the 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 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/Vehicle OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module, Ignition ON/Vehicle in Service Mode.
    2. Test for less than 1 V between the 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.
    • Go to next step: If between 9.5-10.5 V 
  3. Test for less than 1 V between the signal circuit terminal A and ground.
    • If greater than 1 V 
    1. Ignition OFF/Vehicle OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module, Ignition ON/Vehicle in Service Mode.
    2. Test for less than 1 V between the signal circuit and ground.
      • If 1 V or greater, repair the short to voltage in the circuit.
      • If less than 1 V, repair the K73 Telematics Communication Interface Control Module.
    • Go to next step: If less than 1 V 
  4. Test for greater than 8 V between the signal circuit terminal B and the signal circuit terminal A.
    • If less than 8 V 
    1. Ignition OFF/Vehicle OFF, disconnect the connector X2 at the K73 telematics communication interface control module.
    2. Test for infinite resistance between the low 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 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.
    • Go to next step: If greater than 8 V 
  5. Test or replace the B24 Cellular Phone Microphone.
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