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Home >> Jeep >> 2015 >> Grand Cherokee Laredo, AWD >> Repair and Diagnosis >> Engine Performance >> System >> 3.6L - DTCS P0501 To P1128 >> DTC Troubleshooting >> P0685-ASD/Main Control Circuit >> Diagnostic Test
July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

Diagnostic Test

  1. CHECK FOR AN ACTIVE DTC 
    1. Turn the ignition on.
    2. With the scan tool, read DTCs and record on the repair order.

      Is the DTC active or pending?

      Yes 

      • Go To  2

      No 

  2. ASD RELAY 
    1. With the scan tool, erase DTCs.
    2. Turn the ignition off.
    3. Replace the ASD Relay with a know good relay.
    4. Turn the ignition on.
    5. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      • Go To  3

      No 

  3. CHECK THE (K51) ASD CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE 
    1. Turn the ignition off.
    2. Remove the ASD Relay from the PDC.
    3. Disconnect the PCM C1 harness connector.
      CAUTION:

      Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the GPEC Diagnostic Adaptor to perform the diagnosis.

    4. Connect the (special tool #10436, Adapter, GPEC Diagnostic).
    5. Measure the resistance of the (K51) ASD Control circuit between the ASD Relay connector in the PDC and the GPEC Adaptor.

      Is the resistance below 3.0 Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the (K51) ASD Control circuit for an open or high resistance.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECK THE (K51) ASD CONTROL CIRCUIT FOR A SHORT TO ANOTHER VOLTAGE SUPPLY CIRCUIT 
    1. Check for continuity between the (K51) ASD Control circuit and all other circuits at the GPEC Adaptor.

      Is there continuity between the (K51) ASD Control circuit and any other circuit?

      No 

      • Go To  5

      Yes 

      • Repair the (K51) ASD Control circuit for short to the circuit that measured below 10k Ohms.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  5. CHECK THE (K51) ASD CONTROL CIRCUIT FOR A SHORT TO GROUND 
    1. Check for continuity between ground and the (K51) ASD Control circuit at the ASD Relay connector in the PDC.

      Is there continuity between ground and the (K51) ASD Control circuit?

      No 

      • Go To  6

      Yes 

      • Repair the (K51) ASD Control circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. CHECK RELATED PCM AND COMPONENT CONNECTIONS 
    1. Perform any Service Bulletins that apply.
    2. Disconnect all PCM harness connectors.
    3. Disconnect all related in-line harness connections (if equipped).
    4. Disconnect the related component harness connectors.
    5. 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.

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

      Did the DTC return?

      Yes 

      • Replace the Powertrain Control Module in accordance with the Service information. To replace the PCM, refer to GAS . To program the PCM, refer to GAS .
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

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