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Home >> Jeep >> 2016 >> Grand Cherokee SRT >> Repair and Diagnosis >> Engine Performance >> System >> 6.4L - DTCS P0643 To P2167 >> 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. DTC IS ACTIVE 
    1. Ignition on, engine not running.
    2. With the scan tool, erase DTCs in the PCM.
    3. Perform several ignition key cycles, pausing for at least one minute between each cycle.
    4. Turn the ignition on.
    5. With the scan tool, select View DTCs.

      Did this DTC return?

      Yes 

      • Go To  2

      No 

  2. ASD RELAY 
    1. Ignition off.
    2. Install a known good relay in place of the ASD Relay.
    3. Turn the ignition on.
    4. With the scan tool, erase DTCs in the PCM.
    5. Perform several ignition key cycles, pausing for at least one minute between each cycle.
    6. Turn the ignition on.
    7. With the scan tool, select View DTCs.

      Did this DTC return?

      Yes 

      • Go To  3

      No 

  3. CHECK THE (K51) ASD RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND 
    1. Turn the ignition off.
    2. Remove the ASD Relay.
    3. Disconnect the PCM C1 harness connector.
    4. Measure the resistance between ground and the (K51) ASD Relay Control circuit at terminal 85 of the ASD Relay connector.

      Was the resistance above 10k Ohms?

      Yes 

      • Go To  4

      No 

      • Repair the (K51) ASD Relay Control circuit for a short to ground.
      • Perform the PCM VERIFICATION Test. Refer to POWERTRAIN VERIFICATION TEST .
  4. CHECKING THE PCM POWER AND GROUND CIRCUITS 
    1. Install the ASD relay.
    2. Perform the diagnostic procedure for CHECKING THE PCM POWER AND GROUND CIRCUITS. Refer to CHECKING THE PCM POWER AND GROUND CIRCUITS .

      Were any problems found?

      Yes 

      No 

      • Go To  5
  5. POWERTRAIN CONTROL MODULE 
    1. Using the wiring diagram/schematic as a guide, inspect the Powertrain Control Module wiring and connectors.
    2. Look for any chafed, pierced, pinched, or partially broken wires.
    3. Look for broken, bent, pushed out or corroded terminals.
    4. Check for proper PCM power supply from the ignition switch and the ASD relay. Check the PCM for proper ground supply.
    5. Perform any Technical Service Bulletins that may apply.

      Were any problems found?

      Yes 

      No