Deutz-Fahr 593 – ECU: Fuel Metering Unit Powerstage Overtemperature

The Engine Control Unit (ECU) has detected an overtemperature condition in the power level (powerstage) circuit related to the fuel system. This indicates excessive electrical resistance or load in the circuit, leading to an abnormal heat buildup that exceeds the normal operating range. This condition can affect the proper operation of the fuel metering unit (MPROP valve), which regulates fuel volume to the high-pressure pumping elements and controls common rail pressure.

• Deutz TCD 2012 Series (Tier 3)
• Deutz TCD 2013 Series (Tier 3)
• Deutz TCD 6.1 (Stage V)
• 7 Series TTV
• 7250 TTV

1. 1

   Visually inspect the wiring harness and connector at the fuel metering unit (MPROP valve) on the high-pressure pump for damage, corrosion, loose pins, or fretting.

2. 2

   Check for any available Technical Service Bulletins (TSBs) regarding known high-resistance issues with the metering valve connector.

3. 3

   Disconnect the harness and check for continuity on each wire between the ECU connector and the metering unit connector to rule out an open circuit.

4. 4

   Test for short circuits by measuring resistance from each wire to chassis ground and to each other (resistance should be infinite).

5. 5

   Measure the internal resistance of the fuel metering unit across its terminals (typically 2 to 5 Ohms) to check for internal failure.

1. 1

   Safety First

   Ensure the engine is off, the key is removed, and the battery is disconnected to prevent accidental starting. Allow sufficient time for the common rail system pressure to dissipate.

2. 2

   Clean the Area

   Thoroughly clean the area around the high-pressure pump and the fuel metering unit to prevent contamination of the fuel system.

3. 3

   Inspect and Test Wiring

   Perform the diagnostic checks on the wiring harness and connector. If any damage, corrosion, or high resistance is found in the connector or harness, this is the most likely cause of the fault.

4. 4

   Repair Wiring/Connector

   If a faulty connector is identified, replace it using a repair kit (which may include a new connector pigtail and terminals). Ensure all new connections are securely crimped and sealed against moisture.

5. 5

   Replace the Fuel Metering Unit (if necessary)

   If the wiring and connector are confirmed to be in good condition and the metering unit itself is diagnosed as faulty, unplug the electrical connector, remove the retaining screws, and gently remove the old unit. Install the new unit with new O-rings or seals and tighten the retaining screws to the manufacturer's specified torque.

6. 6

   Reassemble and Reset

   Reconnect the electrical connector securely and reconnect the battery. Bleed the low-pressure fuel system to remove any air introduced during the repair. Using a diagnostic tool (like Deutz SerDia), clear the fault code memory and check/reset the pressure relief valve (PRV) opening counter.

7. 7

   Final Test

   Start the engine and let it run, monitoring for the return of the fault code. Check for any fuel leaks.