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Home >> Pontiac >> 2008 >> Grand Prix GXP >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 3 (Engine Controls And Fuel - 3.8L - Troubleshooting & Diagnosis) >> Electronic Ignition (EI) System Diagnosis >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different variant/trim than selected.
  1. ignition OFF, remove the fuel pump.
  2. Crank the engine and test for a spark on each cylinder spark plug wire using the J 26792  Spark Tester. See Special Tools . Ground the companion cylinder spark plug wire of each cylinder when it is tested.
    • If a bright blue spark is present on all cylinders, remove and inspect all of the spark plugs for proper torque, proper gap, wear, damage, and fouling. Refer to Spark Plug Inspection . Replace the spark plugs if necessary.
    • If spark is present on one or more of the cylinders, inspect and test the spark plug wires for arching, cuts, rubbing on other components, and proper resistance, refer to Spark Plug Wire Inspection or a faulty IC module.
  3. Ignition OFF, disconnect the IC module connector. Test for less than 5 ohms of resistance between the IC module low reference circuit and ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  4. Test for less than 3 ohms of resistance between the IC module ground circuit and battery ground.
    • If greater than the specified value, test the ground circuit for an open/high resistance.
  5. Ignition ON, test for B+ between the IC module ignition voltage circuit and ground.
    • If less than the specified range, test the IC module ignition voltage circuit for an open/high resistance or short to ground.
  6. Connect the IC module.
  7. Disconnect the CKP sensor and CMP sensor connectors.
  8. Test for less than 1 ohm of resistance on each low reference circuit.
    • If greater than the specified value, test the low reference circuit for an open/high resistance.
  9. Ignition ON, test for more than 10.0 volts between the 12-volt reference circuit for each sensor and ground.
    • If less than the specified range, test the 12-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the IC module.
  10. Ignition ON, test for 4.0-8.0 volts between each signal circuit 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 IC module.
    • If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the IC module.
  11. Ignition ON, using a jumper wire connected to ground, momentarily touch each sensor signal circuit repeatedly. The CKP Sensor A parameter, CKP Sensor B parameter, and CMP RPM parameter should increment when the appropriate circuit is touched.
    • If the CKP Sensor A parameter increments, replace the CKP sensor.
    • If the CKP Sensor B parameter increments, replace the CKP sensor.
    • If the CMP RPM parameter increments, replace the CMP sensor.
  12. Ignition OFF, Disconnect the IC module connector. Ignition ON, using a jumper wire connected to ground, momentarily touch the medium resolution engine speed signal circuit repeatedly. The CKP Sensor parameter should increment.
    • If the CKP Sensor parameter increments, replace the IC module.
    • If the CKP Sensor parameter does not increment, test the medium resolution engine speed signal for an open/high resistance, short to ground, or a short to voltage. If all circuits test OK, replace the PCM.
  13. Momentarily touch the low resolution engine speed signal circuit repeatedly. The CKP Sensor parameter should increment.
    • If the CKP Sensor parameter increments, replace the IC module.
    • If the CKP Sensor parameter does not increment, test the low resolution engine speed signal for an open/high resistance, short to ground, or a short to voltage. If all circuits test OK, replace the PCM.
  14. Momentarily touch the camshaft position signal circuit repeatedly. The CMP RPM parameter should increment.
    • If the CMP RPM parameter increments, replace the IC module.
    • If the CMP RPM parameter does not increment, test the camshaft position signal circuit for an open/high resistance, short to ground, or a short to voltage. If all circuits test OK, replace the PCM.
  15. If all tests are normal, then the system is operating correctly.
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