John Deere 168.01 – Rear Chassis Control Unit: Control Software, Supply Voltage (BAT) Too Low

The control unit has registered that the supply voltage has dropped below 9 volts. This indicates a severe voltage drop typically caused by a weak or dead battery, a failing alternator, or a wiring/ground fault restricting power to the module.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 6010
• 6110
• 6210
• 6310
• 6410
• 6510
• 6610
• 6810
• 6910
• 6090M
• 6100M
• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 7630
• 7730
• 7830
• 7930
• 7720
• 7820
• 7920
• 7810

1. 1

   Check the resting battery voltage to ensure it is well above the 9-volt threshold (should be 12V+) and perform a load test.

2. 2

   Start the engine and check the alternator output to ensure the battery is receiving a proper charge.

3. 3

   Check the power supply fuses for the transmission and rear chassis control systems (specifically Fuse F9).

4. 4

   Inspect the wiring harness, battery terminals, and the specific connectors plugging into the Rear Chassis Control Unit for corrosion, loose pins, or damaged wires that could cause a voltage drop.

1. 1

   Address the Power Source

   If the battery fails the load test, replace it. If the alternator is not outputting proper voltage while the engine is running, replace the alternator.

2. 2

   Repair Wiring

   Clean all battery terminals and chassis ground connections. If the harness leading to the Rear Chassis Control Unit is damaged, splice and repair the broken wires or replace the harness section.

3. 3

   Replace Fuses

   Replace any blown fuses discovered during the diagnostic phase.

4. 4

   Cycle Power

   Once voltage is restored, cycle the key switch to reboot the system. If the code was simply due to a dead battery, the code should clear and normal transmission operation will resume.

5. 5

   Module Replacement (Worst Case)

   If the battery, alternator, and wiring all test perfectly (showing 12V+ at the module connector) but the PTQ 000168.01 code persists, the Rear Chassis Control Unit itself has suffered an internal hardware failure and must be replaced.