Case IH 2685 – TECU, PTC, or CCU: Transmission lubrication oil pressure low

The transmission lubrication oil pressure has dropped below the minimum acceptable threshold (typically regulated between 15–35 psi on Magnum series, or 10–20 psi on wheel loaders/Steigers depending on the model and RPM).

• Steiger T4B
• Magnum Series (7110, 7120, 7240, MX series)
• Steiger Series (535, 9370, 9380)
• Puma / Maxxum Series

1. 1

   Fluid Level Check: Verify the transmission/hydraulic oil level. Low oil level is the most common cause of a drop in lube pressure.

2. 2

   Filter Inspection: A plugged transmission lube filter or a stuck filter bypass valve will restrict flow and cause low pressure.

3. 3

   Mechanical Pressure Test: Install a mechanical pressure gauge at the transmission lube pressure test port (often marked 'L1' or 'LUBE TD'). Compare the reading at LOW IDLE and HIGH IDLE against the OEM spec for your specific model.

4. 4

   Electrical Circuit Check: If the mechanical gauge shows normal pressure but the fault persists, disconnect the wiring harness at the pressure switch/sensor. Check for continuity to ground or an open circuit in the wiring harness.

5. 5

   Pump Suction Check: Inspect the transmission pump suction lines for air leaks, which can cause aeration and pressure drops.

1. 1

   Park and Secure

   Park the tractor on a level surface, engage the parking brake, lower all implements, and shut off the engine.

2. 2

   Correct Fluid Levels

   If the fluid is low, top it up with the OEM-specified hydraulic/transmission fluid (e.g., Case IH Hy-Tran Ultraction).

3. 3

   Service the Filters

   Drain the filter housing and replace the transmission lube oil filter. Inspect the old filter for heavy brass or steel debris, which would indicate internal clutch or gear failure.

4. 4

   Replace the Sensor/Switch (If Faulty)

   Locate the transmission lube pressure switch (typically at the top rear of the transmission or on the filter base). Disconnect the electrical connector. Unthread the old switch and install the new one (use a thread sealant if required by the manual). Reconnect the wiring harness.

5. 5

   Inspect the Relief Valve (If Mechanical Pressure is Low)

   Locate the transmission lube pressure regulating valve (or cold oil relief valve). Remove the valve plug and extract the spring and spool. Inspect for scoring, broken springs, or debris holding the valve open. Clean the bore and replace the valve/spring if damaged.

6. 6

   Clear Codes and Test

   Turn the key ON, use the cab monitor or an electronic service tool to clear the stored fault codes, and start the engine. Verify that the warning light extinguishes within 15 seconds of starting.