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Home >> Isuzu >> 2007 >> Ascender 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 439 (Cellular System, Entertainment System & Navigation System) >> Diagnostic Information and Procedures >> DTC B1025, B1035, B1045, or B1055 >> Circuit/System Testing
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Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Envoy and 2009 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: If equipped with rear seat audio (RSA), the RSA must be turned off to perform proper speaker testing.

Without Amplifier or RSA

  1. Ignition OFF, disconnect the harness connector at the appropriate speaker.
  2. Radio ON, test for 5.0-7.5 volts between the signal circuit terminal A and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  3. Test for 5.0-7.5 volts between the signal circuit terminal B and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  4. If all circuits test normal, test or replace the speaker.

Without Amplifier with RSA - Front Speaker Testing

  1. Ignition OFF, disconnect the harness connector at the appropriate speaker.
  2. Radio ON, test for 5.0-7.5 volts between the signal circuit terminal A and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  3. Test for 5.0-7.5 volts between the signal circuit terminal B and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  4. If all circuits test normal, replace the speaker.

Without Amplifier with RSA - Rear Speaker Testing

  1. Ignition OFF, disconnect the CJ2 harness connector at the HVAC Control Module.
  2. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    • Left rear low level audio signal (+) - terminal B3
    • Left rear low level audio signal (-) - terminal B7
    • Right rear low level audio signal (+) - terminal B4
    • Right rear low level audio signal (-) - terminal B8
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  3. Ignition OFF, disconnect the harness connector at the appropriate speaker.
  4. Radio ON, test for 5.0-7.5 volts between the signal circuit terminal A and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HVAC Control Module.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC Control Module.
  5. Test for 5.0-7.5 volts between the signal circuit terminal B and ground.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HVAC Control Module.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC Control Module.
  6. If all circuits test normal, replace the speaker.

With Amplifier - Front and Rear Speaker Testing

  1. Ignition OFF, disconnect the X1 harness connector at the amplifier.
  2. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    • Left front low level audio signal (+) - terminal B10 X1
    • Left front low level audio signal (-) terminal B9 X1
    • Right front low level audio signal (+) - terminal B8 X1
    • Right front low level audio signal (-) - terminal B7 X1
    • Left rear low level audio signal (+) - terminal B6 X1
    • Left rear low level audio signal (-) - terminal B5X1
    • Right rear low level audio signal (+) - terminal B4 X1
    • Right rear low level audio signal (-) - terminal B3 X1
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  3. If all circuits test normal, replace the amplifier.

With Amplifier and RSA - Front and Rear Speaker Testing

  1. Ignition OFF, disconnect the X1 harness connector at the amplifier.
  2. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    • Left front low level audio signal (+) - terminal B10
    • Left front low level audio signal (-) terminal B9
    • Right front low level audio signal (+) - terminal B8
    • Right front low level audio signal (-) - terminal B7
    • Left rear low level audio signal (+) - terminal B6
    • Left rear low level audio signal (-) - terminal B5
    • Right rear low level audio signal (+) - terminal B4
    • Right rear low level audio signal (-) - terminal B3
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  3. Ignition OFF, reconnect the X1 harness connector at the amplifier.
  4. Disconnect the CJ2 harness connector at the HVAC Control Module.
  5. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    • Left rear low level audio signal (+) - terminal B3
    • Left rear low level audio signal (-) - terminal B7
    • Right rear low level audio signal (+) - terminal B4
    • Right rear low level audio signal (-) - terminal B8
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the radio.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the radio.
  6. Ignition OFF, reconnect the CJ2 harness connector at the HVAC Control Module.
  7. Disconnect the X1 harness connector at the amplifier.
  8. Radio ON, test for 5.0-7.5 volts between the appropriate signal circuit terminal listed below and ground.
    • Left rear low level audio signal (+) - terminal B6
    • Left rear low level audio signal (-) - terminal B5
    • Right rear low level audio signal (+) - terminal B4
    • Right rear low level audio signal (-) - terminal B3
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the rear seat audio (RSA) module.
    • If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the rear seat audio (RSA) module.
  9. If all circuits test normal, replace the amplifier.
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