John Deere 168.18 – ECU, BCU, BIF, FCC, iTC: Battery Voltage Low / Unswitched Battery Voltage Moderately Low

The control unit has detected a supply voltage that has fallen below the acceptable operational limit (dropping below 9 volts, or between 8V and 9V). When the voltage falls below this threshold, the control unit may restrict engine power, disable functions to protect the system from erratic operations, or trigger a system shutdown.

• 5085E
• 5090E
• 5090EL
• 5100E
• 5085M
• 5100M
• 5100MH
• 5100ML
• 5115ML
• 5090M
• 5115M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5E Series
• 5100E Tier 4 Final
• 6M Series
• 6110M–6195M
• 6020/6030 Series
• 8020 Series
• 8120–8520
• 8RT Series
• 9RT Series
• 244K
• 324K
• 304J
• 444J
• 544J
• 624J
• 9660 CTS
• 7180–7980 Forage Harvesters
• 370E
• 410E
• 460E
• 7400A TerrainCut Mowers

1. 1

   Inspect Battery and Connections: Check the battery's health and state of charge. Ensure that all battery terminals and ground connections are secure, tight, and free of corrosion.

2. 2

   Test the Charging System: Check the alternator output with the engine running to ensure it is maintaining adequate voltage levels (typically around 13.5V - 14.4V).

3. 3

   Evaluate Wiring and Fuses: Look for any damaged wiring harnesses, chafed wires shorting to ground, or blown fuses that could be causing a severe voltage drop to the ECU.

4. 4

   Check for Electrical Drains: Identify any parasitic draws or aftermarket devices that may be draining the battery when the machine is keyed off.

1. 1

   Clean and Tighten

   Disconnect the battery cables (negative first). Clean the battery posts and cable terminals with a wire brush. Reconnect and tighten them securely.

2. 2

   Charge and Load Test

   Fully charge the battery and perform a load test. If the battery fails the load test or cannot hold a charge above 12V, replace it.

3. 3

   Repair Wiring

   If the battery is good but voltage at the ECU harness is still below 9V, trace the power supply circuit. Repair or replace any corroded wires, faulty starter relays, or blown fuses.

4. 4

   Replace Alternator

   If the battery is good but the system voltage drops steadily while the engine is running, replace the faulty alternator.

5. 5

   Clear Codes

   Once the voltage supply is restored, clear the 000168.18 code from the ECU and run the machine to confirm full functionality has been regained.