Massey Ferguson D192 – Instrument Panel (Dash): Pneumatic brake system pressure sensor - Electrical signal too low

The return voltage from the pneumatic brake system pressure sensor (X168) to the controller has dropped below the minimum acceptable threshold. This is most commonly caused by a short to ground in the signal wire, an open circuit (broken wire or disconnected plug), or an internally failed sensor.

• MF 8650
• MF 8680
• Interim Tier 4 (2012-2015)
• 7615
• 5613
• MF 8480
• MF 8450
• 7616
• 7618
• 5608
• 7619
• 7626
• MF 8660
• 7624
• MF 8690
• 7614
• MF 8470
• 5610
• 7620
• MF 8600
• MF 8460
• MF 8670
• 5612
• 7622
• 5611
• 5609
• 8600 Series
• 8670
• 8690
• 7700 / 7700S Series (Tier 4)
• 7714
• 7715
• 7716
• 7718
• 7719
• 7720
• 7722
• 7724
• 7726
• 7600 Series
• Dyna-4 models
• Dyna-6 models

1. 1

   Inspect the pneumatic brake system pressure sensor (X168) electrical connector for water ingress, corrosion, or backed-out pins.

2. 2

   Trace the wiring harness from the sensor toward the cab/dash bulkhead, looking for chafing or pinched wires that could cause a short to ground.

3. 3

   Disconnect the sensor, turn the key to the ON position, and use a multimeter to verify the sensor connector is receiving the proper 5V reference voltage and has a clean ground.

4. 4

   Check the continuity of the signal wire from the sensor connector back to the instrument panel harness to rule out an open circuit.

1. 1

   Depressurize the System

   Chock the tractor wheels and pump the brake pedals/release the air tanks to completely bleed all compressed air from the pneumatic brake system. Do not remove the sensor while the system is under pressure.

2. 2

   Disconnect Battery

   Turn off the ignition and disconnect the negative battery terminal.

3. 3

   Remove the Sensor

   Unplug the electrical connector from sensor X168. Using an appropriately sized wrench, unthread the faulty pressure sensor from the pneumatic port.

4. 4

   Install New Sensor

   Thread the new sensor into the port. If it does not have pre-applied thread sealant, apply a pneumatic-safe thread sealant (avoiding the sensor orifice). Tighten to OEM torque specifications.

5. 5

   Reconnect

   Plug the electrical connector back in, ensuring the locking tab clicks into place. Reconnect the battery.

6. 6

   Test and Clear

   Start the tractor, allow the air compressor to build system pressure, and check for air leaks around the new sensor. Clear the D192 fault code from the dash menu or via a diagnostic tool.