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Home >> Chevrolet >> 2006 >> Epica LT >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 2.5L (LBK) - DTC P0506 To DTC P2110 >> DTC P2070 or P2071 >> Circuit/System Testing

Circuit/System Testing

  1. Ignition ON, verify DTCs P0660, P0661, P0662, P2077, or P2078 are not set.
  2. Ignition OFF, disconnect the harness connector of the intake manifold tuning position sensor.
  3. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit of the IMT valve position sensor and ground.
    • If greater than 5 ohms, test the low reference circuit of the IMT valve position sensor for a short to voltage, or an open/high resistance. If the circuit/connections test normal, replace the ECM.
    4. IMPORTANT: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.
  4. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit of the IMT valve position sensor and the ground.
    • If less than 4.8 volts, test the 5-volt reference circuit of the IMT valve position sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
    • If greater than 5.2 volts, test the 5-volt reference circuit of the IMT valve position sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  5. Using a scan tool, verify the IMT valve position sensor voltage parameter is less than 0.3 volt.
    • If greater than 0.3 volt, test the signal circuit of the applicable IMT valve position sensor for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM.
  6. Install a 3-amp fused jumper wire between the signal circuit and the 5-volt reference circuit of the IMT valve position sensor. Verify the IMT valve position sensor voltage parameter is greater than 4.8 volts.
    • If less than 4.8 volts, test the signal circuit of the IMT valve position sensor for a short to ground. If the circuit/connections test normal, replace the ECM.
  7. If all circuits/connections test normal, test or replace the IMT valve.
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