Case IH 14003 – ICU (Instrument Control Unit): Hydraulic oil filter switch closed to ground on power up

The control module is detecting a ground signal from the hydraulic/transmission oil filter restriction switch immediately at key-on (power up). Because there is no hydraulic pressure when the engine is off, the switch should be in its default open state. A closed state at power-up indicates an electrical short to ground, either within the switch itself or in the wiring harness.

• Magnum
• Steiger T4B
• Magnum 235
• Magnum 250
• Magnum 260
• Magnum 280
• Magnum 290
• Magnum 310
• Magnum 315
• Magnum 340
• Magnum 380
• Steiger Series (350 through 600)
• Maxxum Series
• Puma Series

1. 1

   Disconnect the wiring harness from the hydraulic oil filter switch and turn the key to the ON position (engine off). If the code changes to an open circuit code or goes away, the switch is internally shorted to ground.

2. 2

   If the code remains active with the switch unplugged, trace the wiring harness from the switch back to the ICU/INST controller. Look for rubbed-through wire insulation touching the tractor chassis (ground).

3. 3

   Inspect the switch connector and the ICU pins for corrosion, moisture, or bent pins that could be bridging the circuit to a ground wire.

1. 1

   Power Down

   Turn off the tractor and remove the key.

2. 2

   Locate the Switch

   Locate the hydraulic/transmission oil filter housing. The restriction switch is threaded directly into the filter housing base.

3. 3

   Harness Repair

   If the diagnostic checks revealed a rubbed wire, splice and repair the damaged section of the harness using weather-sealed heat-shrink connectors, then wrap in protective loom.

4. 4

   Switch Replacement

   If the switch is internally shorted, unplug the electrical connector.

5. 5

   Remove Faulty Switch

   Unscrew the faulty switch from the filter housing (have a rag ready, as a small amount of hydraulic oil may weep out).

6. 6

   Install New Switch

   Thread the new OEM switch into the housing and tighten to specification.

7. 7

   Reconnect Harness

   Reconnect the electrical harness.

8. 8

   Filter Maintenance

   Replace the hydraulic oil filter at the same time, as a severely clogged filter can sometimes damage the switch diaphragm.

9. 9

   Clear Codes

   Power the tractor on and verify the 14003 code has moved from 'Active' to 'Stored/Inactive'. Clear the code using the tractor's display monitor or an Electronic Service Tool (EST).