Case IH 49 – TRANS (Transmission Controller): Auto Guidance Isolation valve driver Fault

The controller has detected an electrical malfunction in the driver circuit responsible for operating the Auto Guidance Isolation valve. The underlying condition is typically an open circuit, a short to ground, a short to battery voltage (B+) in the wiring harness, or an internal failure of the valve's solenoid coil.

• MX Magnum
• TG Series
• Steiger
• Puma
• Magnum 235–340 (Series 4)
• Axial-Flow 7010
• Axial-Flow 8010
• Axial-Flow 9120
• T8.xxx Series
• T6000 Series
• T7000 Series

1. 1

   Locate the Auto Guidance Isolation valve, typically installed near the steering orbitrol or on the primary hydraulic distribution valve block.

2. 2

   Inspect the wiring harness and connectors between the Transmission Controller and the isolation valve solenoid for visible damage, corrosion, or pushed-out pins.

3. 3

   Use a multimeter to perform a continuity test on the circuit to check for broken wires (open circuit).

4. 4

   Test the circuit for a short to ground or a short to a 12V power source.

5. 5

   Measure the resistance of the isolation valve solenoid coil itself. If the resistance is out of specification (reading as an open loop or a dead short), the coil has failed internally.

1. 1

   Power down the machine and disconnect the battery to prevent electrical shorts during the repair.

   Power down the machine and disconnect the battery to prevent electrical shorts during the repair.

2. 2

   Locate the Auto Guidance Isolation valve on the hydraulic block or steering orbital.

   Locate the Auto Guidance Isolation valve on the hydraulic block or steering orbital.

3. 3

   Disconnect the electrical harness connector from the faulty solenoid.

   Disconnect the electrical harness connector from the faulty solenoid.

4. 4

   If the wiring harness was found to be damaged during diagnostics, repair the broken wires or replace the damaged connector pigtail.

   If the wiring harness was found to be damaged during diagnostics, repair the broken wires or replace the damaged connector pigtail.

5. 5

   If the solenoid coil failed the resistance test, remove the retaining nut or clip holding the coil to the valve stem.

   If the solenoid coil failed the resistance test, remove the retaining nut or clip holding the coil to the valve stem.

6. 6

   Slide the old solenoid coil off the valve cartridge.

   Slide the old solenoid coil off the valve cartridge. (Note: If the mechanical valve itself is leaking or sticking, the entire valve assembly may need to be unscrewed and replaced, which will require relieving hydraulic system pressure first).

7. 7

   Slide the new OEM solenoid coil onto the valve stem and secure it with the retaining nut/clip.

   Slide the new OEM solenoid coil onto the valve stem and secure it with the retaining nut/clip.

8. 8

   Reconnect the electrical harness to the new solenoid.

   Reconnect the electrical harness to the new solenoid.

9. 9

   Reconnect the battery, start the machine, clear the stored fault codes, and engage the auto-guidance system to verify the fault does not return.

   Reconnect the battery, start the machine, clear the stored fault codes, and engage the auto-guidance system to verify the fault does not return.