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Home >> Chevrolet >> 2006 >> Impala SS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - 5.3L - DTC P1682 To DTC P3401 >> DTC P3401, P3425, P3441, or P3449 >> Circuit/System Testing

Circuit/System Testing

  1. Remove the underhood fuse block cover
  2. With the ignition ON and the engine OFF, test for ignition 1 voltage at both test points of the Emission 2 fuse.
    • If ignition 1 voltage is available to only one test point of the emission 2 fuse, test and repair for a short to ground in the ignition 1 voltage circuit to the VLOM assembly.
    • If ignition 1 voltage is not available to either test point of the emission 2 fuse, test and repair the powertrain relay or the relay load circuit for an open or high resistance condition.
    IMPORTANT: The presence of battery voltage on the ignition 1 voltage circuit to the VLOM connector does not assume that the circuit is free of any high resistance. High resistance could develop anywhere within a circuit, such as in connectors, wiring, relays, solenoids, sensors, modules, or controllers. The first place to test for high resistance would be at any connection point in the circuit. Particular attention should be focused on loose fitting, corroded, or dirty terminals.
  3. To test for total circuit resistance or normal circuit operation, perform the following test:
    • With the ignition ON and the engine OFF, measure and record the ignition 1 voltage at the emission 2 fuse.
    • Remove the emission 2 fuse from the underhood fuse block.
    • Install a DMM, in series with one 15-amp fused jumper wire and one none fuse jumper wire, across the exposed emission 2 fuse terminals in the underhood fuse block.
    • Set-up and select the 10-amp range on the DMM.
    • Zero out the DMM display.
    • With a scan tool, command each DoD cylinder ON, one at a time.
    • Record each amperage reading displayed on the DMM.
    • To calculate the resistance for each solenoid circuit, divide the previously recorded voltage by the amperage for each DoD solenoid circuit. For example, 12 volts divided by 1-amp of current equals 12 ohms of circuit resistance. The total resistance for each solenoid circuit should be within 11-22 ohms.
    • If the total circuit resistance exceeds 22 ohms, an open or a high resistance condition exists somewhere in the ignition 1 voltage circuit, control circuit, solenoid, or the ECM.
  4. 4. With the ignition OFF, reinstall the emission 2 fuse into the underhood fuse block.
  5. Disconnect the wire harness electrical connector at the VLOM assembly. With the ignition ON and the engine OFF, test for battery voltage on the ignition 1 voltage circuit at the VLOM wire harness electrical connector.
    • If the voltage measures less than battery voltage, test and repair the open/high resistance condition in the ignition 1 voltage circuit. All wire circuit resistance should measure less than 2 ohms.
  6. With the ignition ON and the engine OFF, connect one end of a test lamp to the battery positive terminal at the battery. Probe the control circuit for each solenoid at the VLOM wire harness electrical connector.
    • If the test lamp illuminates ON for any control circuit, test and repair that control circuit for a short to ground condition. If each control circuit tests normal, replace the ECM.
  7. With the ignition ON and the engine OFF, connect one end of the test lamp to the battery positive terminal at the battery. Probe each solenoid control circuit at the VLOM wire harness electrical connector. With a scan tool, command the solenoid ON for the circuit that is being probed.
    • If the test lamp does not illuminate when commanded ON, test and repair the control circuit for an open or high resistance condition. All wire circuit resistance should measure less than 2 ohms. If each control circuit tests normal, replace the ECM.
  8. With the ignition ON and the engine OFF, connect one end of the test lamp to the battery negative terminal at the battery. Probe the control circuit for each solenoid at the VLOM wire harness electrical connector.
    • If the test lamp illuminates ON for any control circuit, test and repair the control circuit for a short to battery voltage condition. If each control circuit tests normal, replace the ECM.
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