Case IH 3175 (DTC 4933) - ECU – Electronic Control Unit (ECU A-095): Fan speed signal could not be measured for a period

The control module monitors the cooling fan's speed via a dedicated fan speed sensor (designated as Z-008 in OEM schematics). The speed is measured by calculating the time interval between electronic pulses sent from the sensor. If the control module determines that the time interval between these pulses is too long, falls below the minimum threshold based on engine speed, or has stopped completely, it will log this fault code.

• MAXXUM T4E
• Puma series
• 240 Series Axial-Flow Combines (7120, 7230, 8010, 8120, 8230, 9230, 9240)
• A8000 Sugar Cane Harvester
• A8800 Sugar Cane Harvester

1. 1

   Use the Electronic Service Tool (EST) to check if the fault is currently active. If it is inactive, the issue may be an intermittent wiring problem.

2. 2

   Inspect the cooling fan to ensure it is not physically blocked, jammed, or inoperative.

3. 3

   Visually inspect the wiring harnesses and connectors between the fan speed sensor (Z-008) and the ECU A-095. Look for damage, bent or dislocated pins, corroded terminals, or broken wires. Ensure all connectors are fully seated and locked.

4. 4

   Check the ECU A-095 to ensure it is running the most up-to-date software version, as signal measurement parameters can sometimes be corrected via a software re-flash.

1. 1

   Resolve physical obstructions

   Clear any debris blocking the cooling fan blades to ensure the fan is physically free to spin.

2. 2

   Repair wiring

   If the diagnostic visual inspection reveals damaged wiring or corroded pins at the sensor or the A-095 ECU harness, repair or replace the affected wiring pigtail or terminals.

3. 3

   Replace the sensor

   If the wiring is intact and the fan is physically free to spin, replace the fan speed sensor (Z-008) or the Vistronic fan clutch solenoid, as it has likely failed.

4. 4

   Re-flash or replace ECU

   If the fault has not been resolved after sensor replacement and wiring checks, connect the EST and re-flash the ECU A-095 with the appropriate software. If the ECU cannot be re-flashed or fails to read the new sensor, the A-095 ECU itself must be replaced.

5. 5

   Clear codes

   Clear the fault codes using the EST and run the machine to verify the fan speed signal is reading correctly and the code does not return.