Deutz-Fahr T93 – HLHP Control Unit: 12V power supply fault

The control unit has detected that the 12-volt power supply is absent or interrupted.

• Agroplus 310, 320, 410, and 420 Profiline series tractors
• Agrofarm 410
• Agrofarm 420
• Agrofarm 430
• Agrofarm 85
• Agrofarm 100
• Series 5 Tractors

1. 1

   Cycle the ignition switch OFF, then back ON to see if the fault is a hard fault or an intermittent glitch.

2. 2

   Using a multimeter, check the power supply directly at the HLHP control unit harness to verify that 12V is reaching pins 1, 2, and 15.

3. 3

   Check the wiring harness between the ignition switch, the battery, and the control unit for chafing, corrosion, or loose connections.

1. 1

   Power Down

   Turn the tractor off and remove the ignition key.

2. 2

   Locate the ECU

   Access the HLHP/Transmission control unit.

3. 3

   Inspect Fuses/Relays

   Check the main fuse box for any blown fuses related to the transmission/hydraulic control modules.

4. 4

   Test Harness

   Disconnect the ECU harness. Turn the key to the ON position and probe pins 1, 2, and 15 for 12V.

5. 5

   Trace the Fault

   If 12V is not present at those pins, trace the wiring back to the ignition switch and battery. Repair any broken wires or clean corroded ground/power terminals.

6. 6

   Clear the Code

   Reconnect the harness. Use a compatible diagnostic tool (such as the All Round Tester (ART®) or Serdia 2000/2010) to clear the fault code from the ECU memory.

7. 7

   Verify

   Start the tractor and test the hydraulic shuttle to ensure the code does not return.