Case IH 2806 – Transmission Controller (TRANS): System pressure solenoid is shorted to B+

The transmission controller has detected that the system pressure valve solenoid coil circuit is shorted to battery voltage (B+). When the system pressure valve solenoid coil is commanded ON, the voltage on the low side of the coil is reading higher than expected. This typically points to a shorted solenoid coil, a wiring harness shorted to a power source, or a failed transmission controller.

• Magnum
• Case IH Magnum Series 4 235
• Case IH Magnum Series 4 250
• Case IH Magnum Series 4 260
• Case IH Magnum Series 4 280
• Case IH Magnum Series 4 290
• Case IH Magnum Series 4 310
• Case IH Magnum Series 4 315
• Case IH Magnum Series 4 340
• Case IH Magnum Series 4 370
• Case IH Magnum Series 4 380

1. 1

   Test the solenoid coil resistance by disconnecting the system pressure solenoid connector (C039) and measuring between cavity A and cavity B.

2. 2

   Verify the resistance is approximately 5.9 to 6.5 ohms at 27°C (80°F).

3. 3

   Check for an internal short in the coil (higher resistance than specified or continuity to the solenoid casing).

4. 4

   Inspect the wiring harness between the system pressure valve solenoid and the transmission controller for rubbed insulation causing a short to a 12V power wire (B+).

5. 5

   If the solenoid and wiring test good, check the transmission controller for internal failure.

1. 1

   Park the tractor on a level surface, engage the parking brake, turn off the engine, and disconnect the battery to prevent electrical spikes.

2. 2

   Locate the transmission control valve block and identify the system pressure solenoid.

3. 3

   Disconnect the electrical harness connector from the system pressure solenoid.

4. 4

   If your diagnostics proved the solenoid is shorted, remove the retaining nut/bolt holding the solenoid coil to the valve cartridge.

5. 5

   Slide the old solenoid off the valve stem.

   If replacing the entire cartridge valve, clean the surrounding area, unthread the old valve, lubricate the O-rings on the new valve with clean transmission fluid, and thread it into the block.

6. 6

   Install the new solenoid coil/valve and tighten to the manufacturer's torque specification.

7. 7

   If the solenoid was good but the wiring was shorted, trace the harness back to the transmission controller. Repair any melted, pinched, or bare wires using weather-sealed heat shrink connectors.

8. 8

   Reconnect the electrical connector to the solenoid.

9. 9

   Reconnect the battery, turn the key on, and use your diagnostic tool or the tractor's display to clear the inactive fault codes.

10. 10

    Start the tractor and operate the transmission to verify that system pressure is maintained and the 2806 code does not return.