John Deere 444.04 – RLC (Roof Lighting Controller / Cab Roof Module): Control Software, Supply Voltage (BAT at Terminal J4) Too Low

The code is triggered when the unswitched battery supply voltage at terminal J4 of the module drops below 9 volts. This low voltage condition typically points to a failing battery, poor electrical connections, or a malfunctioning charging system. When active, the control software may experience limited or no functionality, affecting the performance of the cab's electronic systems.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 8245R to 8400R
• 9470RT
• 9520RT
• 9570RT

1. 1

   Check Battery Health: Test the battery to ensure it holds a charge and maintains adequate voltage under load.

2. 2

   Review Electrical Connections: Investigate the battery terminals, chassis grounds, and harness connectors for loose or corroded connections that could impede proper voltage delivery.

3. 3

   Test the Charging System: Verify that the alternator is outputting the correct voltage to keep the system above the 9-volt threshold during operation.

4. 4

   Pinpoint Voltage Test: Measure the unswitched supply voltage directly at Terminal J4 on the RLC (Cab Roof Module) harness connector to confirm if the voltage drop is isolated to the roof harness or is a system-wide issue.

1. 1

   Clean and tighten connections

   Begin by cleaning the battery posts and tightening the battery terminals. Follow the ground cable to the chassis and ensure the connection is clean and tight.

2. 2

   Replace the battery

   If the battery fails a load test or is too old to maintain a charge above 9 volts, replace it.

3. 3

   Repair the wiring harness

   If the battery and alternator are functioning normally, trace the unswitched power circuit leading to the Cab Roof Module (Terminal J4). Look for pinched wires in the cab pillars or corroded pins at the RLC connector. Repair or replace the damaged wiring.

4. 4

   Clear and retest

   Once repairs are made, clear the 000444.04 code from the system. Cycle the key and operate the machine to verify the code does not return and that roof module functions (like lighting) are restored.