Case IH 2704 (6584.04) - DEC – DEC: Auxiliary Pressure #2 Voltage Below Normal, or Shorted To Low range

The DEC is detecting that the signal wire for the Mb Pressure Sensor (Auxiliary Pressure #2) has zero or near-zero voltage. This is caused by either the signal wire shorting directly to a ground source, or the 5V supply wire being completely severed (open circuit), preventing the sensor from powering up and returning a signal.

• VESTRUM CVX
• Magnums
• Steigers
• Axial-Flow combines

1. 1

   Visually inspect the wiring harness leading to the Mb Pressure Sensor (Auxiliary Pressure #2) for chafing, melting, or pinch points against the engine block or frame.

2. 2

   Perform a supply voltage test: Disconnect the sensor, turn the key to the ON position, and measure the voltage at the supply pin on the harness connector (should read a steady 5V reference).

3. 3

   Perform a signal wire short-to-ground test: With the sensor disconnected and the key OFF, measure the resistance (Ohms) between the signal wire pin on the harness and a known good chassis ground.

4. 4

   Check the connector for pushed-back pins, corrosion, or water intrusion, which can simulate an open circuit.

1. 1

   Resolve Wiring Faults

   If the supply wire has no voltage, trace the wire back to the DEC harness connector. Repair the break in the wire or replace the damaged harness section. If the signal wire is shorted to ground, locate the chafed section of the wire where it is touching the chassis or engine block, splice in a new section of wire, and seal it with heat-shrink tubing.

2. 2

   Replace the Sensor

   If the supply voltage is exactly 5V, the ground is good, and the signal wire is not shorted, the sensor has failed internally (shorted to ground inside the sensor body). Remove the old sensor and install the replacement.

3. 3

   Clear the Fault Code

   Reconnect the sensor. Use the Case IH Electronic Service Tool (EST) laptop software to clear the inactive fault codes from the DEC memory, as keypad clearing is often restricted on these modules.