Case IH t37 – PCU (Powertrain Control Unit) or ECU: Boost Air Pressure Sensor (PHY), Shorted To High Source

The control module is receiving a voltage signal from the boost air pressure sensor that exceeds the maximum normal operating threshold. This is typically caused by the sensor's signal wire shorting directly to a power source, a broken ground wire, or an internal failure within the sensor itself.

• MXM
• MXM 120
• MXM 130
• MXM 140
• MXM 155
• MXM 175
• MXM 190

1. 1

   Inspect the wiring harness leading to the boost air pressure sensor for rubbed-through insulation, pinched wires, or melted conduit.

2. 2

   Disconnect the sensor and measure voltage on the signal wire terminal. If high voltage remains, the short is in the harness. If voltage drops to 0V, the sensor is internally shorted.

3. 3

   Verify that the sensor is receiving the correct 5V reference voltage and has a solid ground.

1. 1

   Trace wiring

   If the harness is faulty: Trace the signal wire back toward the ECU to locate the short.

2. 2

   Repair wiring

   If the harness is faulty: Cut out the damaged section of wiring and solder/heat-shrink a new section of wire, or replace the damaged pigtail connector.

3. 3

   Secure harness

   If the harness is faulty: Secure the harness away from hot engine components or vibration points.

4. 4

   Disconnect battery

   If the sensor is faulty: Turn off the tractor and disconnect the negative battery cable.

5. 5

   Clean area

   If the sensor is faulty: Locate the Boost Air Pressure Sensor on the intake manifold piping and clean the area around the sensor to prevent dirt from falling into the intake manifold.

6. 6

   Remove sensor

   If the sensor is faulty: Unplug the electrical connector, remove the retaining bolts or unscrew the sensor, and pull the sensor out of the manifold.

7. 7

   Install sensor

   If the sensor is faulty: Lubricate the O-ring on the new sensor with a small amount of clean engine oil, insert the new sensor, tighten the fasteners to OEM spec, and plug in the electrical connector.

8. 8

   Verify repair

   If the sensor is faulty: Reconnect the battery, start the engine, and verify that the t37 code has cleared (or clear it manually via the tractor's H-Menu diagnostic interface).