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Home >> Pontiac >> 2009 >> G8 GXP, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System & Fuel System - 6.0L, 6.2L - P0340 To DTC P3400 >> DTC P0480 or P0481 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition OFF, disconnect the fan relay.
  2. Ignition ON, verify that a test lamp does not illuminate between the earth terminal and a known ground. If the test lamp illuminates, test the control circuit for a short to voltage.
  3. Ignition ON, Connect a test lamp between the control circuit terminal and a known ground. Command the relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the relay control circuit for a short to voltage. If the circuit tests normal replace the ECM. If the test lamp is always OFF, test the relay control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the ECM.
  4. Connect a test lamp between the Battery + terminal and a known ground. If the test lamp does not illuminates, test the Battery + for a short to ground or an open/high resistance.
  5. Connect a 30-A fusible link wire between the battery positive post and the fan voltage supply circuit terminal and verify fan activation. If the fan does not activate, test the fan voltage supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the fan
  6. If all circuits test normal replace the affected relay.
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