John Deere 3597.03 – Engine Control Unit (ECU) / Engine Control Module (ECM) or Operator Interface Control (OIC): 5 Volt Sensor Supply 1 Out of Range High
Issue description
Indicates a high voltage condition on a 5-volt reference circuit or an ECU power output circuit. The ECU detects a voltage above the specified 5-volt limit on the Sensor Supply 1 circuit, which is almost always caused by a short to a higher voltage source (such as the 12V battery circuit).
Applies to these machines
33 machines- 6110M
- 6120M
- 6130M
- 6145M
- 6155M
- 6175M
- 6195M
- 316GR
- 318G
- 318D
- 320D
- 325
- 328
- 331G
- 333G
- 319D
- 323D
- 319E
- 323E
- 9470RT
- 9520RT
- 9570RT
- 8R Series
- 8RT Series
- 8245R
- 8400R
- 7180
- 7280
- 7380
- 7480
- 7580
- 7780
- 7980
Check the cause
Turn the key switch to the OFF position and disconnect the main Engine Control Unit (ECU) connector.
Identify all sensors sharing the 5 Volt Sensor Supply 1 circuit (e.g., engine speed control pedal, throttle position sensor, pressure/temperature sensors).
Disconnect these sensors one by one.
Use a multimeter to check the 5V supply wire in the main harness for continuity to a 12V power source.
If the voltage drops back to normal (5V) when a specific sensor is unplugged, that sensor is internally shorted.
If the wire itself is receiving 12V while unplugged from the sensors, the wiring harness has rubbed through and is shorting to a 12V wire.
Repair steps
Isolate the Battery
Disconnect the negative battery terminal to prevent accidental shorts during repair.
Repair the Harness
Trace the 5V Sensor Supply 1 wire from the ECU to the sensors. Look for pinch points, chafing against the frame, or melted insulation. Splice and heat-shrink any damaged wires, or replace the affected harness section.
Replace the Faulty Sensor
If the diagnostic checks proved a sensor was internally shorting the 5V circuit to 12V, remove the mounting hardware for that sensor, install the new OEM sensor, and plug in the connector.
Reconnect and Clear Codes
Reconnect the ECU and battery. Turn the key ON and use a diagnostic tool (like John Deere Service ADVISOR) to clear the stored 003597.03 code.
Test Run
Start the machine and verify that the sensor supply voltage remains within the normal 5V range and the code does not return.
Parts you might need
(3)Engine Control Unit (ECU) / Engine Control Module (ECM)
If the module's internal 5V driver has failed
Main Engine Wiring Harness
Fitment: Specific to machine model and serial break
5-Volt Reference Sensors
e.g., Engine Speed Control Pedal / Throttle Position Sensor, Manifold Air Pressure Sensor
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