Case IH 1013 – ISM-DI: Battery 5V Reference 2 Circuit High

The Engine Control Unit (ECU) supplies a steady 5-volt reference signal to power various engine sensors. This code indicates that the voltage on the "Reference 2" circuit is reading higher than the expected 5 volts. This is typically caused by a wire shorting to a 12V battery source, an internally shorted sensor, or an internal failure within the ECU itself.

• skid steer
• SR130
• SR160
• SR175B
• SV series
• TR series
• TV series

1. 1

   Verify System Voltage: Check the battery and alternator output to ensure the vehicle system voltage is normal and not overcharging (which can cause voltage spikes across all circuits).

2. 2

   Inspect the Harness: Visually inspect the engine wiring harness connecting the ECU to the engine sensors. Look for chafing, melted insulation, or pinched wires that could cause the 5V circuit to short to a 12V power wire.

3. 3

   Sensor Isolation Test: Disconnect the sensors that share the 5V Reference 2 circuit one at a time. Monitor the live data or active fault codes. If disconnecting a specific sensor causes the voltage to drop back to normal (or changes the code to a "Circuit Low/Open" code), that sensor is internally shorted.

4. 4

   Check ECU Pins: Inspect the ECU connectors for water ingress, corrosion, or bent pins that could be bridging a 12V pin to the 5V reference pin.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable before servicing the ECU or wiring harness.

2. 2

   Repair Wiring

   If a short to power was found in the harness during diagnostics, splice and repair the damaged section using OEM-approved heat-shrink connectors, or replace the engine harness entirely.

3. 3

   Replace Faulty Sensor

   If the isolation test revealed a shorted sensor, remove the faulty sensor, clean the mounting port, and install the replacement sensor. Reconnect the pigtail.

4. 4

   Replace the ECU

   If the harness and all sensors test good, the ECU has an internal short. Disconnect the harness from the ECU, unbolt the module from its mounting bracket, and install the new ECU. (Note: A new ECU will require dealer programming/flashing using the CNH EST diagnostic tool to restore self-learning parameters and engine datasets).

5. 5

   Clear Codes

   Reconnect the battery, turn the key to the ON position, and use a diagnostic tool to clear the inactive 1013 fault code. Run the engine to verify the code does not return.