Massey Ferguson T238 – TRANS / TRANS2: Issue With Powershift P Solenoid Supply Voltage (TRANS)

Short circuit to +12 V on the X478 - Powershift module solenoid valve (P). The transmission controller logs this code when the measured current on this circuit is > 40 mA in relation to the required value, indicating that voltage is bleeding into the circuit or the solenoid has failed internally.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 5710SL
• 5711SL
• 5712SL
• 5713SL
• 7714
• 7715
• 7715S
• 7716
• 7716S
• 7718
• 7718S
• 7719
• 7720

1. 1

   Inspect the transmission wiring harness leading to the Powershift module, specifically tracing the circuit for the X478 (P) solenoid valve for chafed wires, melted insulation, or pinched lines.

2. 2

   Disconnect the harness at the transmission controller and at the X478 solenoid to inspect the pins for corrosion, water ingress, or bent terminals.

3. 3

   Use a multimeter to measure the resistance of the X478 solenoid valve and compare the reading against OEM specifications to check for an internal short.

4. 4

   With the solenoid unplugged, turn the key ON and probe the signal wire on the harness side. If +12V is present, the short is in the wiring harness. If no voltage is present, the short is internal to the solenoid.

1. 1

   Disconnect Power

   Turn off the tractor and disconnect the negative battery terminal to prevent electrical spikes.

2. 2

   Access the Solenoid

   Locate the Powershift valve block on the side of the transmission housing. Identify the X478 (P) solenoid valve.

3. 3

   Repair Wiring

   If the diagnostic checks revealed a short in the harness, repair the damaged section of the wire using weather-sealed heat shrink connectors, or replace the affected transmission harness pigtail.

4. 4

   Replace the Solenoid

   If the solenoid is internally shorted: Clean the area around the valve block to prevent debris from entering the transmission. Unplug the electrical connector from the X478 solenoid. Remove the retaining bolts/nut holding the solenoid coil to the valve cartridge. Slide the old solenoid off and install the new replacement part. Torque the retaining nut to OEM specifications and reconnect the harness.

5. 5

   Reassemble and Clear Codes

   Reconnect the battery, turn the ignition ON, and use a diagnostic tool to clear the T238 fault code. Start the tractor and cycle the Powershift transmission through its ranges to verify the repair.