John Deere 158.03 – PL1 Control Software / Gear Shift Module Direct Drive: Supply Voltage (ELX) Too High

The control software has registered a switched supply voltage (ELX) exceeding 16.0 volts. This is an overvoltage condition, which is typically caused by an overcharging alternator, a failed voltage regulator, or a wiring issue.

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

1. 1

   Visually inspect the area around the batteries and alternator for any damage, loose connections, or accumulated debris

2. 2

   Test the voltage at the battery terminals using a multimeter while the tractor engine is running (readings consistently above 15.5V - 16.0V indicate overcharging)

3. 3

   Inspect the wiring harness leading to the PL1 module and the Vehicle Load Center (VLC) to ensure there are no shorts to a higher voltage source and that battery connections are correct

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the negative battery cable to prevent electrical shorts during repair.

2. 2

   Address the Charging System

   Remove the serpentine/drive belt from the alternator pulley. Disconnect the electrical connectors from the rear of the alternator. Unbolt and remove the alternator assembly. Note: Depending on the exact alternator model, you may be able to replace just the voltage regulator on the back of the unit. Otherwise, replace the entire alternator assembly.

3. 3

   Install New Components

   Mount the new alternator (or repaired unit with a new regulator), reconnect the electrical plugs, and reinstall the drive belt, ensuring proper tension.

4. 4

   Reconnect and Test

   Reconnect the battery. Start the tractor and measure the voltage at the battery again. It should now read a healthy charging voltage (typically between 13.5V and 14.5V).

5. 5

   Clear Codes

   Use a John Deere Service Advisor tool or the tractor's onboard diagnostic display to clear the stored 000158.03 fault code.