John Deere 5125.03 – Engine Control Unit (ECU): Sensor Supply #7 Voltage Out of Range High
Issue description
The 5-volt reference supply voltage for Sensor Circuit 7 is reading out of its upper limit, which almost always points to a short circuit to a 12-volt power source.
Applies to these machines
40 machines- 5085E
- 5090E
- 5090EL
- 5100E
- 5085M
- 5100M
- 5100MH
- 5100ML
- 5115ML
- 6110M
- 6120M
- 6130M
- 6145M
- 6155M
- 6175M
- 6195M
- 6110R
- 6120R
- 6130R
- 6145R
- 6155R
- 6175R
- 6195R
- 6215R
- 8235R
- 8245R
- 8260R
- 8270R
- 8285R
- 8295R
- 8310R
- 8320R
- 8335R
- 8345R
- 8360R
- 8370R
- 8400R
- 8310RT
- 8335RT
- 8360RT
Check the cause
Inspect the wiring harness and connectors associated with Sensor Supply #7 (routing to Manifold Air Pressure and Crank Case Pressure sensors) for damaged, frayed, or melted insulation causing a short to 12V.
Perform a sensor isolation test by disconnecting the Manifold Air Pressure Sensor, Crank Case Pressure Sensor, and EGR Flow Meter one at a time. If voltage returns to 5V, the disconnected sensor is internally shorted.
Test the pins at the ECU to ensure the controller itself is outputting the correct 5V reference and is not internally shorted.
Repair steps
Turn off the engine and disconnect the battery to ensure safety.
Locate the sensors on the Sensor Supply #7 circuit (Manifold Air Pressure Sensor, Crank Case Pressure Sensor).
Carefully unloom and inspect the wiring harness leading to these sensors.
Look for any visible signs of chafing against the engine block or exposed wires causing a short to a 12V source.
Repair or replace any damaged wiring or connectors.
Insulate the repairs properly.
If the wiring is intact but the isolation test (above) proved a sensor was internally shorted to voltage, replace the faulty sensor.
Reconnect all sensors and the battery.
Turn the key to the ON position and use a diagnostic tool to clear the ECU fault codes.
Start the engine and monitor the system to ensure the code does not return and the engine operates normally.
Parts you might need
(5)Manifold Air Pressure Sensor
RE522723Fitment depends heavily on the specific engine/machine model; fits 7030/8030 series.
Manifold Air Pressure Sensor
RE537639Fitment depends heavily on the specific engine/machine model; fits 8R series.
Manifold Air Pressure Sensor
DZ111910Fitment depends heavily on the specific engine/machine model.
Crank Case Pressure Sensor
Varies by specific engine model (verify exact part number with a John Deere dealer using your machine's serial number).
EGR Flow Meter
Varies by specific engine model (verify exact part number with a John Deere dealer using your machine's serial number).
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