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Home >> Alfa Romeo >> 2019 >> Giulia Base, AWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 10 (2.9L Pcm 1 - DTCS P0351-00 To P06DB-00) >> DTC Troubleshooting >> P0642-00-Sensor Reference Voltage 1 Circuit Low >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different variant/trim than selected.
  1. CHECK FOR AN ACTIVE DTC 
    1. With the scan tool, read Powertrain Control Module 1 (PCM-1) DTCs and Freeze Frame Data and record on the repair order.
    2. Using the recorded Freeze Frame Data and the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
    3. With the scan tool, read PCM-1 DTCs.

      Is the DTC active or pending?

      Yes 

      • Go To  2

      No 

  2. CHECK THE (F343) FUSED ASD RELAY OUTPUT CIRCUIT FOR AN OPEN OR SHORT 
    1. Turn the ignition off.
    2. Disconnect the PCM-1 C1 harness connector.
    3. Using a 12-volt test light connected to ground, probe the (F343) Fused ASD Relay Output circuits at the PCM-1 harness connector.

      Does the test light illuminate brightly?

      Yes 

      • Go To  3

      No 

      • Repair the (F343) Fused ASD Relay Output circuits for an open or short.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  3. CHECK THE (Z108) GROUND CIRCUITS FOR AN OPEN/HIGH RESISTANCE 
    1. Using a 12-volt test light connected to 12 volts, probe the (Z108) Ground circuits at the PCM-1 harness connector.

      Does the test light illuminate brightly at each ground circuit?

      Yes 

      • Go To  4

      No 

      • Repair the (Z108) Ground circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all PCM-1 harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    5. Connect all PCM-1 harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs.
    9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    10. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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