How to Perform a Detroit GHG17 Parked SCR Efficiency Test

The Detroit GHG17 Engine Parked SCR Efficiency Test verifies the integrity of the Selective Catalytic Reduction (SCR) system from engine warm-up to NOx efficiency. This test helps identify SCR catalyst efficiency concerns and DEF concentration issues.

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Important Notes

• Total test time: 60-85 minutes.
• Ensure the engine is at operating temperature (coolant temperature at least 71°C or 160°F) for accurate results.
• Perform a Parked Regeneration if the DPF light is on before starting the test.

Test Procedure

1. Access the SCR System Tab
   • In the Service Routines window, navigate to the SCR System tab.
   • Select “Perform Parked SCR Efficiency Test” from the drop-down menu.
2. Start the Test
   • Press the Start button.
   • A “Caution” dialog box will appear.
     
3. Safety Precautions
   • Ensure the transmission is in Park or Neutral and the parking brake is engaged.
   • Press “Yes” to continue or “No” to exit.
     
4. Activate the Test
   • Press and hold the DPF switch in the “ON” position for 5 seconds, then release it. The engine speed will increase, indicating that the routine has begun.
5. Monitor Test Progress
   • The test will run, and the current status will be displayed in the progress box.
   • Note: If the test is aborted, the progress field will display a description of where the test failed.
     
6. Test Outcome
   • The test is not classified as passed or failed. After the test finishes and after 1 hour of stabilization, the progress field may display “NOx concentrations not high enough”.
     

Troubleshooting

• If the progress box displays “Routine not started” or “Routine stopped”, check the following:
  1. High Idle Safety Conditions:
     • Ensure the parking brake, neutral switch, clutch status, vehicle speed, and engine idle conditions are set as required in the service documentation.
  2. Component Error Codes:
     • Look for the error code “DEF pump and DEF metering valve error not active” in the SCR system and resolve it.
  3. Ignition Cycle:
     • Perform an ignition cycle, ensure communications from all modules are disabled, then turn the ignition back on and start the routine.
  4. Parked Regeneration:
     • If the above steps do not work, perform a Parked Regeneration before starting the routine.
• If Fault 520372/16 – SCR Closed Loop at Maximum Limit is active (not “persistent”) and other specific codes are not active, perform the following:
  • Perform a Parked Regeneration and allow the system to idle for 30 minutes.
  • Turn the ignition off and on again before starting the service routine.

By following these steps, you can effectively perform a Parked SCR Efficiency Test on a Detroit GHG17 engine, ensuring the integrity and efficiency of the SCR system.

More repair cases for Detroit Diesel engines,please refer to:Detroit Diesel Engine Repair