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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 434 (6.7L Diesel - DTCS P0420 To P1208 - 2500 Hd & 3500 Hd) >> Diagnosis And Testing >> P0687- ECM Main Control Circuit High >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. ACTIVE DTC 
    1. Turn the ignition on, engine not running.
    2. With the scan tool, record all Freeze frame data.
    3. With the scan tool, erase DTCs.
    4. Turn the ignition off for 75 seconds.
    5. Turn the ignition on, engine not running.
    6. With the scan tool, read DTCs.

      Did DTC P0686 reset?

      Yes 

      • Go To  2

      No 

  2. SCR RELAY 1 
    1. Turn the ignition off.
    2. Use a known good relay in place of the SCR Relay 1.
    3. Turn the ignition on, engine not running.
    4. With the scan tool, record all Freeze frame data.
    5. With the scan tool, erase DTCs.
    6. Start and run the engine until it reaches operating temperature.
    7. Using the scan tool, read DTCs.

      Did DTC P0687 reset?

      Yes 

      • Go To  3

      No 

      • Repair Complete.
      • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to STANDARD PROCEDURE .
  3. CHECK THE (K401) SCR RELAY 1 12-VOLT SUPPLY CIRCUIT FOR SHORT TO VOLTAGE 
    1. Disconnect the PCM C2 harness connector.
    2. Disconnect the SCR Relay.
    3. Measure for voltage on the (K401) SCR Relay 1 12-Volt Supply circuit at pin 82 of the PCM C2 harness connector.

      Is there voltage present?

      Yes 

      • Repair the (K401) SCR Relay 1 12-Volt Supply circuit for a short to voltage.
      • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to STANDARD PROCEDURE .

      No 

      • Go To  4
  4. POWERTRAIN CONTROL MODULE 
    1. Reconnect the SCR Relay 1.
    2. Turn the ignition on, engine not running.
    3. Measure the voltage on the (K401) SCR Relay 1 12-Volt Supply circuit at pin 82 of the PCM C2 harness connector.

      Is the voltage higher than battery voltage?

      Yes 

      • Check relay operation at the Power Distribution Center.
      • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to STANDARD PROCEDURE .

      No 

      • Replace the Powertrain Control Module in accordance with the service information.
      • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to STANDARD PROCEDURE .
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