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Home >> Chevrolet >> 2019 >> Bolt EV Premier >> Repair and Diagnosis >> External Pages >> Different car >> Section 1 (Cellular System, Entertainment System, And Navigation System) >> Diagnostic Information and Procedures >> DTC B1277 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2018 Chevrolet Bolt EV. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: B24 Mobile Telephone Microphone
  3. Ignition - On/Vehicle - In Service Mode
  4. Test for 8.0 to 10.5 V between the test points: Signal circuit terminal B & Ground
    • If less than 8.0 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X1 @ A11 Radio
    3. Test for infinite resistance between the test points: Signal circuit terminal B & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Signal circuit terminal B & The other end of the circuit
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Replace the component: A11 Radio
    • If greater than 10.5 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X1 @ A11 Radio
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Signal circuit terminal B & Ground
      • If 1 V or greater - Repair the short to voltage on the circuit.
      • If less than 1 V - Replace the component: A11 Radio
    • Go to next step: If between 8.0 and 10.5 V 
  5. Test for less than 1 V between the test points: Low Reference circuit terminal A & Ground
    • If greater than 1 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X1 @ A11 Radio
    3. Ignition - On/Vehicle - In Service Mode
    4. Test for less than 1 V between the test points: Low Reference circuit terminal A & Ground
    5. If 1 V or greater - Repair the short to voltage on the circuit.
    6. If less than 1 V - Replace the component: A11 Radio
    • Go to next step: If less than 1 V 
  6. Test for greater than 8 V between the test points: Signal circuit terminal B & Low Reference circuit terminal A
    • If less than 8 V 
    1. Ignition/Vehicle & All vehicle systems - Off
    2. Disconnect the electrical connector: X1 @ A11 Radio
    3. Test for infinite resistance between the test points: Low Reference circuit terminal A & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • Go to next step: If infinite resistance
    4. Test for less than 2 ohms between the test points: Low Reference circuit terminal A & The other end of the circuit
    5. If 2 ohms or greater - Repair the open/high resistance in the circuit.
    6. If less than 2 ohms - Replace the component: A11 Radio
    • Go to next step: If greater than 8 V 
  7. Test or replace the component: B24 Mobile Telephone Microphone
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