Diagnostic Test

WARNING: This page is about a different car, the 2015 RAM 3500 HD and 2015 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

ACTIVE DTC
NOTE:
If DTC P21CA, P21CB, or P21CC are also active, diagnose and repair that DTC before continuing with this test procedure.
1. Turn the ignition on, engine not running.
2. With the scan tool, actuate the DEF Line Heater or Tank Heater Override Test.
3. With the scan tool, View DTCs.
  Is the DTC Active?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITION - 6.7L. Refer to INTERMITTENT CONDITION - 6.7L .
CHECK THE (F203) SCR MODULE HEATER SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the PDC C5 harness connector.
3. Disconnect the DEF Dosing Control Unit C1 harness connector.
4. Measure the resistance of the (F203) SCR Module Heater Supply circuit between the PDC C5 harness connector and the DEF Dosing Control Unit C1 harness connector.
  Is the resistance below 5.0 Ohms?
  
  Yes
  - Go To 3
  No
  - Repair the (F203) SCR Module Heater Supply circuit for an open or high resistance.
  - Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to POWERTRAIN VERIFICATION TEST - 6.7L .
CHECK THE (F203) SCR MODULE HEATER SUPPLY CIRCUIT FOR A SHORT TO GROUND
1. Measure the resistance between ground and the (F203) SCR Module Heater Supply circuit at the DEF Dosing Control Unit C1 harness connector.
  Is the resistance above 10k Ohms?
  
  Yes
  - Go To 4
  No
  - Repair the (F203) SCR Module Heater Supply circuit for a short to ground.
  - Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to POWERTRAIN VERIFICATION TEST - 6.7L .
CHECK THE PDC OUTPUT
1. Reconnect the PDC C5 harness connector.
2. Turn the ignition on and start the engine.
3. Measure the voltage of the (F203) SCR Module Heater Supply circuit at the DEF Dosing Control Unit C1 harness connector.
  Is the voltage approximately equal to battery voltage?
  
  Yes
  - Replace the DEF Dosing Control Unit in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to POWERTRAIN VERIFICATION TEST - 6.7L .
  No
  - Check the fuse (F19-30A) in the PDC that feeds the SCR 1 (Heater) Relay. Check the connectors at the DEF Dosing Control Unit and PDC for spread terminals causing an intermittent connection. If the fuse and connectors are good, replace the Power Distribution Center (PDC) in accordance with the service information.
  - Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to POWERTRAIN VERIFICATION TEST - 6.7L .