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Home >> Jeep >> 2014 >> Grand Cherokee Laredo, RWD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 7 (DRIVEABILITY - Diesel - Non-DTC Based Diagnostics) >> Diagnosis And Testing >> Checking The Pcm Power And Ground Circuits >> Diagnostic Test

Diagnostic Test

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  1. PCM GROUND CIRCUIT(S) OPEN 
    1. Turn the ignition off.
    2. Disconnect the PCM C1 harness connector.
    3. Using a 12-volt test light connected to 12-volts, probe each of the PCM ground circuits in PCM C1 connector cavities 2, 4 and 6.

      Did the test light illuminate for each cavity?

      Yes 

      • Go To  2

      No 

      • Repair the PCM Ground circuit(s) for an open.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
  2. FUSED IGNITION SWITCH START/RUN OUTPUT CIRCUIT OPEN 
    1. Turn the ignition off.
    2. Turn the ignition to the Start position.
    3. Using a 12-volt test light connected to ground, check the (F942) Fused Ignition Run/Switch Output circuit at the PCM C1 harness connector (cavity 54).
    4. Turn the ignition to the Run position.
    5. Using a 12-volt test light connected to ground, check the (F942) Fused Ignition Run/Switch Output circuit at the PCM C1 harness connector (cavity 54).

      Is the test light on for both ignition switch positions?

      Yes 

      • Go To  3

      No 

      • Repair the (F942) Fused Ignition Run/Switch Output circuit for an open.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
  3. CHECKING THE ASD RELAY SYSTEM 
    1. Turn the ignition off.
    2. Connect a jumper between ground and the (K51) ASD Relay Control circuit in PCM C1 harness connector (cavity 28) to close the relay.
    3. Turn the ignition on.
    4. Using a 12-volt test light connected to ground, probe the (F342) and (F344) ASD Relay Output circuits at the PCM C1 harness connector (cavities 1, 3 and 5).

      Does the test light illuminate brightly for each circuit?

      Yes 

      • Test Complete.

      No 

      • Go To  4
  4. FUSED ASD RELAY BATTERY SUPPLY CIRCUIT OPEN 
    1. Turn the ignition off.
    2. Remove the ASD Relay.
    3. Using a 12-volt test light connected to ground, probe the Fused ASD Relay Battery Supply circuit at ASD Relay connector (terminal 30).

      Does the test light illuminate brightly?

      Yes 

      • Go To  5

      No 

      • Repair the Fused ASD Relay Battery Supply circuit for an open.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
  5. ASD RELAY OUTPUT CIRCUIT OPEN 
    1. Connect a jumper between cavity 30 and cavity 87 at the ASD Relay connector.
    2. Using a 12-volt test light connected to ground, probe the (F342) and (F344) ASD Relay Output circuits at the PCM C1 harness connector (cavities 1, 3 and 5).

      Did the test light illuminate for each circuit?

      Yes 

      • Go To  6

      No 

      • Repair the (F342) or (F344) ASD Relay Output circuit for an open.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
  6. ASD RELAY CONTROL CIRCUIT OPEN 
    1. Turn the ignition off.
    2. Remove the ASD Relay.
    3. Measure the resistance of the (K51) ASD Relay Control circuit between the ASD Relay connector and the PCM C1 harness connector.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Replace the ASD Relay.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .

      No 

      • Repair the ASD Relay Control circuit for an open.
      • Perform the PCM VERIFICATION TEST. Refer to appropriate Engine Diagnostic information .
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