John Deere 000158.03 – PLC: High Ignition Supply in PLC

The Rear Chassis Module (PLC) has detected a voltage in its switched ignition supply circuit that is higher than the normal operating range (Voltage Above Normal, or Shorted to High Source). This abnormal voltage level, which can sometimes exceed 32V, can affect the proper operation of the system and is typically caused by an overcharging alternator, a wiring short to a high voltage source, or an internal failure within the control module itself.

• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 5R Series
• 6M Series
• 6R Series
• 7M Series
• 7R Series
• 8R Series
• 9R Series

1. 1

   Perform an initial reset by turning the ignition key off, waiting a few moments, and turning it back on to see if the code clears (intermittent issue)

2. 2

   Check battery voltage with the engine off (should be at least 12.6V)

3. 3

   Test the charging system with the engine running at approximately 1,500 RPM. Voltage at the battery terminals should be between 13.8V and 14.5V. A reading above 15.0V indicates an overcharging situation (e.g., faulty voltage regulator)

4. 4

   Inspect ground connections for the chassis and control modules to ensure they are clean, tight, and free of corrosion

5. 5

   Check the connectors at the PLC for any signs of corrosion, moisture ingress, or pushed-out/damaged pins

6. 6

   Inspect the wiring harness leading to the PLC for any chafed, melted, or broken wires that could be shorting to a higher voltage source

1. 1

   Isolate the fault

   Use a diagnostic tool like John Deere Service ADVISOR to retrieve more detailed information on the fault code and system status.

2. 2

   Test the PLC circuit

   Using a multimeter, carefully check the voltage at the ignition supply pin of the Rear Chassis Module connector. Compare this reading to the battery and charging system voltage to determine if the high voltage is system-wide or isolated to the PLC circuit.

3. 3

   Replace the Rear Chassis Module (PLC)

   If the charging system is functioning correctly (no overcharging) and all wiring and connections are sound, the Rear Chassis Module (PLC) likely has an internal failure and must be replaced.