Massey Ferguson T108 – TRANS1: Reverse Clutch Solenoid Amp Draw Issue

The transmission control system has detected an abnormal electrical current (amperage) draw on the circuit for the reverse clutch solenoid valve (X557). The measured current exceeds the maximum possible limit (> 1.4 Amps), indicating a short circuit in the wiring or an internal short within the solenoid coil itself.

• 7616
• 5612
• 7622
• Interim Tier 4 (2012-2015)
• 7614
• 5611
• 7615
• 5610
• 5613
• 7620
• 5609
• 7618
• 5608
• 7619
• 7626
• 7624
• 7614 through 7626
• 7714 through 7726
• 5400
• 5700
• 6400
• 6600
• 6700

1. 1

   Inspect the wiring harness leading to the reverse solenoid valve (X557) for chafing, melted insulation, or bare wires that could be shorting to the tractor chassis (ground) or another power source.

2. 2

   Disconnect the plug at the reverse solenoid and check for water ingress, corrosion, or bent pins. Do the same at the TRANS1 module connector.

3. 3

   Using a multimeter, measure the internal resistance of the reverse solenoid coil. A reading of near-zero ohms indicates an internal short.

4. 4

   Measure the live amp draw; if it spikes above 1.4 A when reverse is commanded, the solenoid is faulty.

5. 5

   Perform a swap test: Temporarily swap the forward (X556) and reverse (X557) solenoid electrical connectors. If the fault code changes to T107, the solenoid is definitively the culprit. If the code remains T108, the issue is in the wiring harness or the TRANS1 controller.

1. 1

   Secure tractor

   Park the tractor on a level surface, engage the parking brake, and turn off the engine.

2. 2

   Locate valve block

   Locate the transmission control valve block (Power Shuttle control unit) on the side of the transmission housing.

3. 3

   Identify solenoid

   Identify the reverse solenoid valve (X557). It is typically located right next to the forward clutch solenoid and the control unit pressure connectors.

4. 4

   Clean area

   Thoroughly clean the area around the valve block to prevent dirt from entering the hydraulic system.

5. 5

   Disconnect wiring

   Disconnect the electrical wiring harness plug from the reverse solenoid.

6. 6

   Remove retaining hardware

   Remove the retaining flange or mounting bolts securing the proportional solenoid valve to the block.

7. 7

   Remove faulty solenoid

   Carefully pull the faulty solenoid valve out of the bore. Have a rag ready to catch any residual transmission oil.

8. 8

   Install new solenoid

   Lubricate the O-rings on the new OEM solenoid valve with clean transmission fluid and insert it into the bore.

9. 9

   Secure new solenoid

   Reinstall the retaining flange/bolts and torque to OEM specifications.

10. 10

    Reconnect wiring

    Reconnect the electrical harness.

11. 11

    Clear code and test

    Clear the T108 fault code using a diagnostic tool and test the tractor's reverse engagement to ensure smooth operation and no returning codes.