John Deere 158.04 – PLD Module: Switched Supply Voltage Low

The control unit has detected that the switched battery supply voltage (ignition voltage) has dropped below the normal operating threshold—typically below 9.0 volts. This low voltage condition can impair the functionality of the control unit, leading to slow or unresponsive behaviors, inadequate processing capabilities, and the risk of system shutdowns.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R

1. 1

   Visual Inspection: Inspect around the batteries and alternator for any visual signs of damage, loose connections, or accumulated debris.

2. 2

   Charging System Test: Check the machine's charging system, battery condition, and alternator output to ensure the system can maintain proper voltage under load.

3. 3

   Relay and Fuse Check: Verify the voltage at the fuse box and transmission enable relays. A faulty relay can cause high resistance (e.g., showing continuity but dropping voltage under load).

4. 4

   Harness Inspection: Inspect the wiring harness leading to the PLD module for chafed wires or shorts to ground.

5. 5

   Pin-Point Voltage Test: Disconnect the connector to the PLD module and verify that the switched power pin is receiving adequate voltage (well above 9.0V, ideally matching battery voltage around 11.75V - 12.6V) when the key is ON.

1. 1

   Power Down

   Turn off the tractor, remove the key, and disconnect the negative battery cable to ensure safety while working on the electrical system.

2. 2

   Clean Connections

   Clean and tighten all battery terminals, chassis ground connections, and alternator connections.

3. 3

   Replace Faulty Power Components

   If the diagnostic checks revealed a blown fuse or a transmission enable relay with high internal resistance, replace it.

4. 4

   Repair Wiring

   If a chafed wire was found in the harness supplying the PLD module, splice and repair the wire using weather-sealed heat shrink connectors, then re-loom the harness to prevent future rubbing.

5. 5

   Address Charging System

   If the battery fails a load test or the alternator is not outputting sufficient voltage, replace the defective component.

6. 6

   Reassemble and Clear Codes

   Reconnect the PLD module and the battery. Turn the key switch ON (or cycle tractor power) to allow the modules to wake up. Clear the fault codes via the CommandCenter™ display and test drive the tractor to verify the code does not return.