Case IH 518506-04 - BCM – BCM: Cab Delta Pressure Sensor signal out of range - low

The control module is receiving a signal voltage from the cab pressure sensor that has dropped below the minimum acceptable threshold. This is typically caused by a failed sensor, a short circuit to ground in the sensor wiring, or a disconnected harness.

• MAGNUM AFS Connect
• Axial-Flow Combine 5088
• Axial-Flow Combine 6088
• Axial-Flow Combine 7088
• Axial-Flow Combine 7230
• Axial-Flow Combine 8230
• Axial-Flow Combine 9230
• Magnum Tractors
• Puma Tractors

1. 1

   Visually inspect the cab delta pressure sensor and wiring harness for chafing, rodent damage, or pinched wires

2. 2

   Disconnect the sensor and inspect the connector pins for corrosion, moisture ingress, or pushed-back terminals

3. 3

   Turn the key to the ON position and use a multimeter to check the sensor connector for a 5V reference signal from the BCM and a good ground

4. 4

   If the 5V reference is missing or pulled down, check the signal wire for continuity to ground to identify a short-to-ground condition

1. 1

   Power Down

   Turn off the machine and disconnect the battery ground cable to prevent electrical spikes during repair.

2. 2

   Access the Sensor

   Remove the necessary cab roof panels or HVAC access covers to reach the cab delta pressure sensor.

3. 3

   Remove the Sensor

   Unplug the electrical connector. Remove the mounting screws or retaining clips holding the sensor to the HVAC housing/air duct.

4. 4

   Install the New Sensor

   Seat the new sensor into the housing, ensuring any O-rings or foam seals are properly aligned to prevent air leaks that could skew pressure readings. Secure the mounting hardware.

5. 5

   Reconnect

   Plug the electrical harness back into the sensor. Reconnect the battery.

6. 6

   Clear Codes & Test

   Connect the Case IH Electronic Service Tool (EST) to clear the inactive 518506-04 fault code from the BCM. Turn on the HVAC system and verify that the cab pressurizer blower motor operates correctly and the code does not return.