John Deere 002392.05 – CCU / ICC: Backup Alarm Circuit Fault

The controlling electronic unit has detected a malfunction in the electrical circuit for the reverse backup alarm. This condition is typically caused by an open circuit, a shorted circuit, or a failed component within the backup alarm system. When this fault is present, the backup alarm function is degraded, and the system may log the issue as the alarm horn current being below normal or an open circuit.

• 3033R
• 3038R
• 3039R
• 3045R
• 3046R
• 3120
• 3320
• 3520
• 3720
• 4044M
• 4044R
• 4049R
• 4052M
• 4052R
• 4066M
• 4066R
• 4120
• 4320
• 4520
• 4720
• 7210J
• 8130
• 8230
• 8330
• 8430
• 8530
• 8225R
• 8245R
• 8270R
• 8295R
• 8320R
• 8335R
• 8345R
• 8370R
• 8400R
• 9230
• 9330
• 9430
• 9530
• 9630
• 9R Series
• 9RT Series
• 9RX Series
• Articulated Dump Trucks
• Backhoe Loaders
• Crawlers
• Skidders
• 204L

1. 1

   Restart the machine to rule out a temporary communication glitch

2. 2

   Check for other diagnostic trouble codes, particularly low voltage codes that may indicate a broader electrical issue

3. 3

   Inspect battery terminals and ground connections for tightness and corrosion (a loose battery ground is a known cause)

4. 4

   Visually inspect the backup alarm (often located on a rear cross member) and its wiring harness for damage, corrosion, dirt, or broken wires at the connector

5. 5

   Inspect the fuse associated with the backup alarm circuit (e.g., F20 fuse on models like the 204L)

6. 6

   Test the circuit using a multimeter for approximately 12 volts at the alarm's power terminal when the ignition is on and the transmission is in reverse, and check for continuity in the ground circuit

7. 7

   Test the backup alarm switch for proper operation (there should be continuity across the switch terminals when activated)

8. 8

   Check in-cab settings on the digital display to ensure the backup alarm is enabled

1. 1

   Park Safely

   Park the machine on a level surface, engage the parking brake, and turn off the engine.

2. 2

   Gain Access

   If necessary, remove any covers or panels to access the backup alarm, which is typically located at the rear of the machine. On a 3033R, for example, this involves removing a cover held by two screws and one 7mm screw.

3. 3

   Disconnect and Inspect

   Disconnect the electrical connector from the backup alarm. Inspect the connector terminals for corrosion, damage, or moisture. Clean as necessary.

4. 4

   Test or Replace the Alarm

   If the wiring and connections appear to be in good condition, the alarm unit itself is the most likely cause of the failure. If a known good alarm is available, connect it to the harness to see if the fault clears. Alternatively, if diagnostic tests point to a faulty alarm, replace it with a new unit.

5. 5

   Clear Codes

   After replacing the alarm, reconnect the battery if it was disconnected, start the machine, and check if the fault code has cleared. On some models, you may need to manually clear the codes through the diagnostic menu.

6. 6

   Verify Operation

   Engage the reverse gear to confirm that the new alarm sounds correctly.