John Deere 3512.04 – ECU / VCU / ECM / XSC: Sensor Supply Voltage 4 Out of Range Low

The control unit has detected that the voltage on the 5-volt sensor supply circuit #4 has dropped below the acceptable specification (typically below 4.75V or 4.59V). This condition almost always indicates a short to ground in the wiring harness, a shorted sensor pulling the voltage down, or an internal failure of the control unit's voltage regulator.

• 6110M
• 6120M
• 6130M
• 6145M
• 6155M
• 6175M
• 6195M
• 6110R
• 6120R
• 6130R
• 6145R
• 6155R
• 6175R
• 6195R
• 6215R
• 316GR
• 318G
• 331G
• 333G
• 318D
• 319D
• 320D
• 323D
• 5M Series
• 5085M
• 5100M
• 6000 Series
• 9RT Series
• 9470RT
• 9520RT
• 9570RT
• PowerTech 9.0L Diesel Engine

1. 1

   Identify Circuit #4 Sensors: Consult your specific machine's technical manual to determine exactly which sensors are powered by the #4 5-volt supply.

2. 2

   Visual Inspection: Inspect the wiring and connectors associated with the 5-volt supply for any signs of damage, chafing, corrosion, or loose connections.

3. 3

   Monitor Voltage: Use a diagnostic tool to monitor the voltage levels of the 5-volt supply in real-time.

4. 4

   Check for Shorts to Ground: Test the specific power supply wires for continuity to ground.

1. 1

   Isolate the short

   Turn the machine's key to the ON position (engine off) so the code is active.

2. 2

   Disconnect sensors

   Unplug the sensors on the #4 supply circuit one at a time.

3. 3

   Monitor the code/voltage

   If the 5-volt supply returns to normal (or the active code changes to an 'Out of Range High' or open circuit code) immediately after unplugging a specific sensor, that sensor has an internal short and must be replaced.

4. 4

   Test the harness

   If all sensors on the circuit are unplugged and the voltage remains low, the short is in the wiring harness. Trace the harness back to the ECU, looking for areas where the wire insulation has rubbed through against the frame or engine block. Repair the damaged wire.

5. 5

   Test the ECU

   If the harness tests perfectly for continuity and has no shorts to ground, the voltage regulator inside the ECU/VCU has likely failed. Contact a John Deere dealer to verify the module failure and program a replacement control unit.