John Deere 3353.14 – BCU / RCU: Alternator Malfunction / Alternator Field Off When Sent a Command to Turn On.

The control unit has commanded the alternator (Component G02) to charge, but it is not detecting the expected voltage output or field current. This indicates that the alternator is failing to charge the battery and power the electrical system, or there is an open/short in the exciter wire circuit.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6230
• 6330
• 6430
• 7130
• 7230
• 7330
• 9470 STS
• 9570 STS
• 9670 STS
• 9770 STS
• 9870 STS

1. 1

   Check the alternator drive belt for proper tension, glazing, or severe wear. A slipping belt will prevent the alternator from charging.

2. 2

   Test the batteries (G01) to ensure they are holding a charge and do not have a dead cell. Clean and tighten all battery terminals.

3. 3

   With the engine running, use a multimeter to check the voltage directly at the alternator's main charge post (B+ terminal) and the battery. It should read between 13.5V and 14.5V.

4. 4

   Verify that the D+ pin on the alternator is receiving voltage from the key switch/relay when the ignition is turned on (exciter circuit check).

5. 5

   Inspect the wiring harness between the alternator and the BCU/RCU for chafing, corrosion, or disconnected plugs.

1. 1

   Disconnect Power

   Turn off the ignition and disconnect the negative (-) battery cable to prevent electrical shorts.

2. 2

   Remove Wiring

   Disconnect the main charge wire (B+) and the electrical connector (D+ / exciter wire) from the rear of the alternator.

3. 3

   Remove the Belt

   Use a breaker bar or wrench to release the tension on the serpentine belt tensioner. Slip the belt off the alternator pulley.

4. 4

   Unbolt the Alternator

   Remove the upper and lower mounting bolts securing the alternator to the engine bracket. Carefully remove the heavy unit from the machine.

5. 5

   Install the New Alternator

   Position the new alternator into the mounting bracket and hand-tighten the mounting bolts. Torque the bolts to OEM specifications.

6. 6

   Reinstall the Belt

   Route the drive belt back over the new alternator pulley, ensuring the ribs seat perfectly into the grooves. Release the tensioner.

7. 7

   Reconnect Wiring

   Reattach the B+ charge wire and the electrical connector.

8. 8

   Test

   Reconnect the negative battery cable. Start the engine and use a multimeter to verify the charging voltage is now 13.5V–14.5V. Ensure the 003353.14 fault code has cleared from the display.