John Deere 5745.06 – ECU: DEF Dosing Unit Heater Circuit Has Low Resistance

The circuit resistance for the Diesel Exhaust Fluid (DEF) dosing unit heater is too low, indicating a short to ground in the heater circuit. The ECU will typically trigger an engine power derate to protect the emissions system until the issue is resolved.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5090M
• 5100M
• 5100MH
• 5100ML
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6M Series
• 6105M
• 7R Series
• 8R/8RT/8RW Series
• 8245R to 8400R
• 9R/9RT/9RX Series
• 9470RT
• 9520RT
• 9570RT
• 310L
• 410L
• 344L
• 130G
• Vermeer D24x40 S3
• Vermeer D40x55 S3

1. 1

   Inspect the wiring harness and connectors running from the ECU to the DEF dosing unit/supply module for damaged, frayed, or melted wires shorting to ground.

2. 2

   Disconnect the harness at the DEF dosing unit and test the resistance and continuity across the heater pins on the unit itself to check for an internal short.

3. 3

   With the unit disconnected, test the harness side for continuity to ground to ensure the short isn't in the main wiring loom.

4. 4

   Verify the electrical supply to the DEF dosing unit is stable and within the correct voltage specifications (12V or 24V).

1. 1

   Disconnect Power

   Disconnect the machine's battery to ensure safety while working on the electrical and emissions systems.

2. 2

   Locate the Component

   Locate the DEF dosing unit (supply module), which is usually mounted directly to the top or side of the DEF tank.

3. 3

   Disconnect Lines and Harness

   Carefully disconnect the electrical harness plug. Disconnect the DEF pressure and return lines. Note: DEF is highly corrosive to certain metals and degrades plastics; clean up any spills immediately with warm water.

4. 4

   Remove the Unit

   Unbolt the mounting hardware securing the DEF dosing unit to the tank header and remove the faulty assembly.

5. 5

   Install the New Unit

   Seat the new DEF dosing unit pump/heater assembly and secure it with the mounting hardware.

6. 6

   Reconnect

   Reattach the DEF fluid lines and plug in the electrical harness.

7. 7

   Clear Codes

   Reconnect the battery. Use a diagnostic scan tool to reset the ECU, clear the 005745.06 fault code, and run the machine to monitor the system and ensure the heater operates normally without throwing a code.