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Circuit/System Testing

WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
  1. Ignition OFF, disconnect the harness connector at the CMP sensor.
  2. Test for less than 1 ohm on the CMP low reference circuit terminal B and ground.
    • If greater than the specified value, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  3. Ignition ON, test for 4.8-5.2 volts between the CMP 5-volt reference circuit terminal A and ground.
    • If less than the specified range, test the 5-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  4. Ignition ON, test for 4.8-5.2 volts between the CMP signal circuit terminal C and ground.
    • If less than the specified range, test the signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
  5. Ignition OFF, connect a fused jumper wire to the CMP signal circuit terminal C.
  6. Ignition ON, momentarily touch the other the other end of the fused jumper wire to the battery negative post. The CMP Active counter, should increment.
    • If the CMP Active counter increments, test or replace the CMP sensor.
    • If the CMP Active counter does not increment, replace the ECM.
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