Case IH 4952 – Instrument Cluster (IC) / Universal Control Module (UCM): Hydraulic Enable (Mechanical Machines) - Hydraulic Interlock Solenoid Open Circuit

The control module has detected a break in the electrical circuit (open circuit) supplying the hydraulic interlock solenoid. This safety mechanism inhibits the loader's hydraulic system and disables boom/bucket movement when the operator is out of the seat or the seat restraint bar is raised. When this circuit is open, the machine will likely lock out hydraulic functions as a fail-safe and trigger an Amber master telltale warning lamp.

• skid steer
• Skid Steer Loaders (SSL)
• Compact Track Loaders (CTL)
• SR130
• SR150
• SR175
• SV185
• SR200
• SR220
• SR250
• SV250
• SV300
• TR270
• TR320
• TV380

1. 1

   Disconnect the electrical connector at the Hydraulic Interlock Solenoid (connector X-PORT_LK) and measure the resistance across the pins of the solenoid coil.

2. 2

   Evaluate the resistance: If it is greater than 8 Ω or reads as 'OL' (infinite resistance), the solenoid has an internal open circuit and must be replaced.

3. 3

   If the solenoid resistance is under 8 Ω, the open circuit is in the wiring harness. Disconnect the main controller connector (e.g., X-C23) and the solenoid connector, then use a jumper wire to bridge the pins and measure resistance through the harness to locate the broken wire or loose pin connection.

1. 1

   Prepare the machine

   Park the machine on a level surface, lower the loader arms completely to the ground, and turn off the engine.

2. 2

   Relieve hydraulic pressure

   Turn the key to the ON position (engine off) and cycle the joysticks/pedals to relieve any residual hydraulic pressure in the system.

3. 3

   Locate the solenoid

   Locate the Hydraulic Interlock Solenoid on the main hydraulic control valve block.

4. 4

   Disconnect the wiring harness

   Disconnect the machine's wiring harness from the faulty solenoid.

5. 5

   Remove the retaining nut

   Remove the retaining nut at the end of the valve stem that holds the solenoid coil in place.

6. 6

   Remove the faulty solenoid coil

   Slide the faulty solenoid coil off the hydraulic valve cartridge. (Note: You generally do not need to remove the hydraulic cartridge itself, which prevents fluid loss).

7. 7

   Install the new solenoid coil

   Slide the new replacement solenoid coil onto the cartridge and secure it with the retaining nut.

8. 8

   Reconnect the electrical harness

   Reconnect the electrical harness.

9. 9

   Clear fault codes

   Clear the fault codes from the Instrument Cluster / UCM.

10. 10

    Test the machine

    Start the machine, lower the seat restraint bar, and test the loader hydraulic functions to confirm the interlock system enables properly and the 4952 code does not return.