Mack Diagnostic Trouble Code – DEF Line Heater Voltage Above Normal Or Shorted High
Details
- Park vehicle on level surface, turn ignition OFF, set parking brake and block wheels.
- Connect scan tool, turn ignition ON with engine OFF and record all circuit related active and inactive fault codes. Turn ignition OFF. If any codes are Voltage Supply Codes. Diagnose these codes first. Go to step 14. If no Voltage Supply Codes exist go to next step.
NOTE: If multiple active fault codes are present a shared open or shorted supply, return, or ground circuit is possible.
- Verify there is no visible damage to component. Ensure proper component operation. Repair/replace faulty components; go to step 14. If components are good go to next step.
- Disconnect ACM connector and inspect wiring harness connectors and Terminals for damage, moisture, proper Terminal tension, and corrosion. If damage is found, clean and repair as required. Go to step 14. If no damage is found, go to next step.
- Disconnect Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector and inspect wiring harness connectors and Terminals for damage, moisture, proper Terminal tension, and corrosion. If damage is found, clean and repair as required. Go to step 15. If no damage is found, go to next step.
- Connect ACM connector. Disconnect Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector. Turn ignition ON. Measure voltage between Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector 12 Volt supply, Terminal B and Terminal A. Record voltage measurement. Turn ignition OFF. If voltage is 12 Volts, replace sensor. Go to step 13. If voltage is NOT 5 Volts, go to next step.
NOTE: Measure towards ACM.
- Disconnect ACM connector. Turn ignition ON. At ACM, measure voltage between ACM SPLY 1 ACTUATORS, Terminal 52 and ACM HEATER OUTPUT1, Terminal 24. Record voltage measurement, turn ignition OFF. If voltage is 12 Volts, go to next step. If voltage is NOT 12 Volts, contact an authorized OEM service center for authorization to replace ACM. Go to step 13.
NOTE: Measure towards ACM.
- With ACM connector and Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector disconnected, measure sensor resistance between Diesel Exhaust Fluid (DEF) Line Heater 1, Terminal A and Diesel Exhaust Fluid (DEF) Line Heater 1, Terminal B of sensor connector. Verify resistance is less than 10 Ohms. If resistance is more than 10 Ohms, clean/replace sensor. Go to step 13. If resistance is less than 10 Ohms, go to next step.
NOTE: Measure towards sensor.
- With ACM connector and Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector disconnected, measure resistance between Diesel Exhaust Fluid (DEF) Line Heater 1, Terminal A harness connector and a good ground. Repeat this step for Diesel Exhaust Fluid (DEF) Line Heater 1, Terminal B harness connector. If resistance is less than 100 k-Ohms repair short to ground. Go to step 13. If resistance is more than 100 k-Ohms. Go to next step.
NOTE: Measure towards ACM.
- With ACM connector and Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector disconnected, measure signal circuit resistance between ACM HEATER OUTPUT1, Terminal 24 harness connector and Diesel Exhaust Fluid (DEF) Line Heater 1, Terminal B sensor harness connector. If resistance is more than 10 Ohms, repair or replace open circuit or excessive resistance in harness, go to step 13. If resistance is less than 10 Ohms, go to next step.
NOTE: Measure across harness.
- With ACM connector and Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector disconnected, measure signal circuit resistance between ACM SPLY 1 ACTUATORS, Terminal 52 harness connector and Diesel Exhaust Fluid (DEF) Line Heater 1, Terminal B sensor harness connector. If resistance is more than 10 Ohms, repair or replace open circuit or excessive resistance in harness, go to step 13. If resistance is less than 10 Ohms, go to next step.
NOTE: Measure across harness.
- With ACM connector and Diesel Exhaust Fluid (DEF) Line Heater 1 harness connector disconnected, measure signal circuit resistance between ACM HEATER OUTPUT1, Terminal 24 and all other Terminals on ACM Harness connector. Measure supply circuit resistance between ACM SPLY 1 ACTUATORS, Terminal 52 and all other Terminals on ACM Connector Harness connector. Verify resistance is more than 100 k-Ohms. If resistance is less than 100 k-Ohms, repair short in harness and go to step 13. If resistance is more than 100 k-Ohms, go to next step.
NOTE: Measure towards harness.
- Connect ACM Connector and Diesel Exhaust Fluid (DEF) Line Heater 1 harness connectors, go to next step.
- Clear fault codes and verify code is NOT active. If code is still active, repeat diagnostics to verify diagnostics were performed correctly. If code is still active, contact an authorized OEM service center for verification of diagnosis and authorization to replace ACM.
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