Massey Ferguson C242 – Cab Suspension Controller: Rear-Left Cab Suspension Range Error

The Cab Suspension Controller has detected a range error from the position sensor on the rear-left cab shock absorber, indicating that the measured or reported value is outside the expected operational range. This angular potentiometer provides feedback on cab height and movement; an implausible signal (too high, too low, or erratic) typically causes the system to disable the suspended cab functionality and illuminate a console warning light.

• 7600 Series
• 5400 Series
• 6400 Series
• 7400 Series
• 8600 Series
• 8670
• 8400 Series

1. 1

   Visually inspect the rear left cab suspension cylinder, sensor, and associated wiring harnesses/connectors (designated as X690 on MF 7600 series) for damage, corrosion, or loose connections

2. 2

   Scan for related fault codes (e.g., C233, C234, C235 for electrical faults on the rear-left unit, or C244 for the rear-right)

3. 3

   Verify the sensor's supply voltage and ground connection at the connector using a multimeter

4. 4

   Monitor the sensor's signal output while the system operates to check for erratic variations instead of a steady signal

5. 5

   Check for relevant service bulletins, such as SB 17-0031 (8600 series) regarding loose restrictor plugs causing constant cab movement

6. 6

   Attempt to recalibrate the cab suspension system; failure (codes C246/C247) strongly suggests a hardware issue

1. 1

   Support cab safely

   Safely support the tractor's cab according to the manufacturer's workshop manual procedures before working on any suspension components.

2. 2

   Repair electrical faults

   If diagnostic checks revealed damaged wiring or corroded connectors, repair or replace these components first. Clear the fault codes and re-test the system.

3. 3

   Inspect and replace restrictor plugs

   On applicable models (e.g., 8600 series), inspect the SRE1 and SRE2 restrictor plugs in the cab suspension block. If loose, replace them with the updated, longer plugs.

4. 4

   Replace sensing cylinder

   If wiring and restrictors are confirmed to be in good condition, replace the rear left-hand suspended cab unit (shock absorber/cylinder assembly).

5. 5

   Calibrate suspension system

   After replacing any components, perform a full calibration of the cab suspension system using the tractor's diagnostic interface or a dealer-level scan tool to ensure new components are recognized.