Case IH 2948 (3510.03) - DEC – Engine Control Unit (ECU): Sensor Supply #2 Voltage Out of Range High

The Engine Control Unit (ECU) supplies a regulated 5.0V reference voltage to various engine sensors. This code triggers when the ECU detects that the voltage on the Sensor Supply #2 circuit has exceeded the upper limit (typically greater than 5.26 volts), indicating that the 5V reference wire has shorted to a higher voltage source, such as a 12-volt battery circuit.

• MAXXUM T4E
• VESTRUM CVX
• Magnum
• Steiger
• Puma
• Maxxum
• Farmall
• Axial-Flow 5130
• Axial-Flow 7120
• Axial-Flow 8010
• Axial-Flow 8120
• Axial-Flow 9230
• Case loaders
• Case backhoes
• Case skid steers

1. 1

   Monitor the voltage on the Sensor Supply #2 circuit using a diagnostic tool or multimeter to verify if it is reading above 5.26V.

2. 2

   Perform a sensor isolation drop-out test by disconnecting the Intake Manifold Air Pressure (MAP) Sensor and Engine Oil Pressure Sensor one at a time. If voltage drops to 5.0V, the disconnected sensor is internally shorted.

3. 3

   Inspect the wiring harness between the ECU and the sensors for chafing, melting, or pinched areas where the 5V supply wire could be rubbing against a 12V power wire.

4. 4

   Perform pin testing by disconnecting the ECU and sensors, and checking for continuity between the 5V supply pin and the 12V battery pins to pinpoint the short.

1. 1

   Power Down

   Turn off the machine, remove the key, and disconnect the negative battery cable to prevent electrical damage during repair.

2. 2

   Repair the Short

   If a sensor was internally shorted, remove and replace it. If the harness was at fault, locate the damaged section, cut out the damaged wires, and splice in new wire using weather-sealed heat-shrink butt connectors, or replace the affected pigtail.

3. 3

   Reassemble

   Reconnect all sensor connectors and the ECU harness. Ensure the wiring is routed away from high-heat sources like the exhaust manifold and sharp metal edges to prevent future chafing.

4. 4

   Verify

   Reconnect the battery, turn the key to the ON position, and use your diagnostic tool to clear the inactive fault codes. Verify that the Sensor Supply #2 voltage now reads a steady 5.0V (± 0.2V).