P20B5

P20B5-(DIESEL EXHAUST FLUID) REDUCTANT PUMP HEATER CONTROL CIRCUIT OPEN




For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation

The Diesel Exhaust Fluid (DEF) Supply Pump Assembly has an internal heater to prevent the fluid from freezing inside the pump. The power supply and control circuits are controlled by the DEF Dosing Control Unit. The DEF Supply Pump Heater is integrated into the DEF Supply Pump Assembly and is not serviced separately. The DEF Dosing Control Unit will illuminate the MIL light via the Powertrain Control Module (PCM) immediately after the diagnostics runs and fails and the line heater will be disabled. The DEF Dosing Control Unit will turn off the MIL light via the PCM when the monitor runs and passes in three consecutive key cycles.

- When Monitored:
Continuously with the ignition on.

- Set Condition:
The DEF Dosing Control Unit detects that the DEF Supply Pump heater circuit is open or shorted to ground.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Turn the ignition on, engine not running.
2. With the scan tool, navigate to Actuator Tests and actuate the DEF Supply Pump Heater.
3. With the scan tool, View DTCs.

Is the DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION - 6.7L. Intermittent Condition Test

2. CHECK THE RESISTANCE OF THE DEF SUPPLY PUMP HEATER
1. Turn the ignition off.
2. Disconnect the DEF Supply Pump Assembly harness connector.
3. Measure the resistance across the terminals of the DEF Supply Pump Heater circuits at the DEF Supply Pump Assembly.

Is the resistance above 2.0 Ohms?

Yes

- Go To 3

No

- Replace the DEF Supply Pump Assembly. Diesel Exhaust Fluid Pump Assembly - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE (K472) DEF SUPPLY PUMP HEATER RETURN CIRCUIT FOR A SHORT TO GROUND




1. Disconnect the DEF Dosing Control Unit C1 harness connector.
2. Measure the resistance between ground and the (K472) DEF Supply Pump Heater Return circuit at the DEF Supply Pump Assembly harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 4

No

- Repair the (K472) DEF Supply Pump Heater Return circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. CHECK THE (K471) DEF SUPPLY PUMP HEATER SUPPLY CIRCUIT FOR A SHORT TO GROUND




1. Disconnect the DEF Dosing Control Unit C1 harness connector.
2. Measure the resistance between ground and the (K471) DEF Supply Pump Heater Supply circuit at the DEF Supply Pump Assembly harness connector.

Is the resistance above 10k Ohms?

Yes

- Go To 5

No

- Repair the (K471) DEF Supply Pump Heater Supply circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK THE (K472) DEF SUPPLY PUMP HEATER RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Measure the resistance of the (K472) DEF Supply Pump Heater Return circuit between the DEF Supply Pump Assembly harness connector and the DEF Dosing Control Unit C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the (K472) DEF Supply Pump Heater Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. CHECK THE (K471) DEF SUPPLY PUMP HEATER SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE




1. Measure the resistance of the (K471) DEF Supply Pump Heater Supply circuit between the DEF Supply Pump Assembly harness connector and the DEF Dosing Control Unit C1 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Replace the DEF Dosing Control Unit. Diesel Exhaust Fluid Dosing Control Unit - Removal.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair the (K471) DEF Supply Pump Heater Supply circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.