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Home >> Chevrolet >> 2006 >> Silverado 1500 HD, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 937 (Engine Controls And Fuel - 4.8L, 5.3L, 6.0L And 6.2L - DTC P0231 To DTC P1255) >> DTC P0351-P0358 >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2007 GMC Sierra, 2007 GMC Cab & Chassis Sierra, 2007 Chevrolet Silverado, and 2007 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect the wire harness electrical connector at the ignition module/coil assembly for the cylinder that is identified as misfiring.
  2. With the key ON, engine OFF, measure for battery positive voltage on the ignition 1 voltage circuit at the ignition module/coil wire harness electrical connector.
    • If the voltage measures less than battery positive voltage, then repair an open, high resistance, or short to ground.
  3. With the key ON, engine OFF, measure the voltage on the IC circuit at the ignition module/coil wire harness electrical connector.
    • If the voltage measures more than 1 volt, then test and repair, if necessary the short to voltage in the IC circuit. If the circuit test normal, then replace the ECM.
  4. Disconnect the fuel injector wire harness electrical connector for the misfiring cylinder that you are working on.
  5. Start and idle the engine. Measure the frequency on the IC circuit at the ignition module/coil wire harness electrical connector, using the DC scale position on the DMM. The frequency should measure between 3-20 Hz.
    • If the frequency measures less than 3 Hz, then test and repair if necessary the IC circuit for an open, high resistance, or short to ground. All wire circuit resistance should measure 2 ohms or less.
    • If the circuit tests normal, then replace the ECM.
    • If the frequency measures more than 20 Hz at idle, then replace the ECM.
  6. With the key ON, engine OFF, probe the low reference circuit with a test lamp that is connected to battery positive voltage.
    • If the test lamp does not illuminate, then test and repair the low reference circuit for an open or high resistance. All wire circuit resistance should measure 2 ohms or less.
    • If the circuit tests normal, then replace the ECM.
  7. Turn OFF the ignition.
  8. Connect the fuel injector wire harness electrical connector that was previously disconnected.
  9. Exchange the ignition module/coil of the affected misfiring cylinder with an ignition module/coil assembly of a good cylinder.
  10. Start and idle the engine.
  11. Observe the misfire counters for the 2 cylinders that the ignition module/coil assemblies were exchanged on.
    • If the engine misfire transfers to the new cylinder with the suspected ignition module/coil assembly, then replace that ignition module/coil assembly.
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