Fendt 0F.1.2B – A038 - ECU, central electrical system: Mirror heater faulty

Electrical malfunction (such as an open circuit, short circuit, or high resistance) in the circuit responsible for heating the exterior rearview mirrors, which are used to clear frost and condensation.

• 922 Vario COM III
• 924 Vario COM III
• 927 Vario COM III
• 930 Vario COM III
• 933 Vario COM III
• 936 Vario COM III
• 300 Vario / SCR Series
• 309
• 310
• 311
• 312
• 313
• 400 Vario Series
• 411
• 412
• 413
• 414
• 415
• 700 Vario / SCR Series
• 714
• 716
• 718
• 720
• 722
• 724
• 800 Vario / SCR Series
• 815
• 818
• 819
• 820
• 822
• 824
• 826
• 828
• 900 Vario COM III / SCR Series
• 916
• 920
• 922
• 924
• 926
• 927
• 930
• 933
• 936
• 939

1. 1

   Inspect the exterior heated mirror glass for cracks or visible damage to the internal heating grid

2. 2

   Inspect the wiring harness leading from the cab to the exterior mirrors, paying close attention to door hinges, pivot points, and mirror arm joints for chafed or broken wires

3. 3

   Perform an element continuity test by removing the mirror glass and measuring resistance across the heating element (infinite resistance indicates a burned-out element)

4. 4

   Test for 12V supply voltage at the mirror harness connectors with the tractor running and mirror heater switched on

5. 5

   If no voltage is present at the mirror harness, check for blown fuses on the central electrical board and inspect the A038 ECU harness connectors for pushed-out or corroded pins

1. 1

   Disconnect Power

   Turn off the tractor ignition and disconnect the battery ground to prevent accidental short circuits.

2. 2

   Remove the Faulty Mirror Glass

   Carefully pry the mirror glass/insert out of the plastic mirror housing. Use a wide, flat plastic trim tool to avoid damaging the housing clips.

3. 3

   Disconnect Wiring

   Unplug the two electrical spade connectors attached to the back of the heated mirror glass.

4. 4

   Repair Wiring (If Applicable)

   If you found broken wires during your diagnostic checks (especially near the mirror pivot), splice and heat-shrink the broken wires, or replace the damaged sub-harness.

5. 5

   Install New Mirror Glass

   Plug the electrical wires into the terminals on the back of the new heated mirror insert. (Polarity usually does not matter for a simple resistive heating element, but match the original orientation if marked).

6. 6

   Reassemble

   Align the new mirror glass with the actuator/mount inside the housing and press firmly until it snaps securely into place.

7. 7

   Test Operation

   Reconnect the battery, turn on the ignition, and activate the mirror heater via the cab controls. Verify that the mirror glass warms up and that the 0F.1.2B fault code changes from "Active" to "Stored" (or clears entirely).