Case IH 12690 – Chassis Control Module or Pneumatic/CTIS Controller: Pneumatic output - delivery port - rear left - leakage (e.g., while trying to hold pressure)

The machine's pneumatic system is detecting an unexpected drop in air pressure on the rear left circuit. When the system closes the valves to hold a specific pressure, the air escapes, pointing to a physical leak in the lines, fittings, or the retaining valve itself.

• Case IH tractors equipped with advanced pneumatic systems

1. 1

   Pressurize the system and listen for audible air hissing near the rear left axle, wheel hub (if CTIS), or rear left cab suspension airbag.

2. 2

   Spray a soapy water solution over the rear left pneumatic delivery port, connecting hoses, and fittings. Look for bubbling which indicates the exact source of the leak.

3. 3

   Monitor the rear left retaining valve to check if the valve is internally bypassing air instead of holding pressure.

1. 1

   Depressurize the System

   Safely bleed all air pressure from the tractor's pneumatic system before disconnecting any lines to prevent injury.

2. 2

   Isolate the Leak

   Based on the soap test, determine if the leak is at a hose, a fitting/O-ring, or the valve block itself.

3. 3

   Replace the Component

   If a line/fitting is leaking: Remove the damaged pneumatic line or fitting. Clean the port threads, install the new fitting with appropriate thread sealant or O-rings, and attach the new line. If the valve is leaking: Disconnect the electrical harness and pneumatic lines from the rear left retaining valve. Unbolt the valve assembly and install the replacement unit.

4. 4

   System Test

   Turn the tractor on, allow the air compressor to build system pressure, and command the rear left port to hold pressure.

5. 5

   Clear Codes

   Verify there are no leaks with soapy water, and use a diagnostic tool to clear code 12690 from the ECU.