Case IH 67 – PTO / Shuttle Module: PTO speed mismatch error

The controller detects that the Power Take-Off (PTO) speed and the engine speed do not match after 6 seconds of operation in manual mode. The tractor's computer monitors the engine RPM via the 'W' terminal on the alternator and compares it to the output from the PTO speed sensor. If there is too great a differential between these two inputs, the controller assumes a fault (or clutch slippage) and disengages the PTO to prevent damage.

• MX Maxxum
• MX80C
• MX90C
• MX100
• MX100C
• MX110
• MX120
• MX135
• MX150
• MX170
• MX180
• MX200
• MX210
• MX215
• MX220
• MX230
• MX240
• MX245
• MX255
• MX270
• MX275
• MX285
• C80
• C90

1. 1

   Check the Alternator 'W' Terminal Signal (Engine RPM source): Test the Hertz (Hz) reading at the 'W' terminal using a multimeter. Expected readings: 1100 RPM = 277–338 Hz, 1500 RPM = 378–462 Hz, 2200 RPM = 554–677 Hz. If readings are 0 Hz or out of spec, the alternator or its internal pickup is faulty.

2. 2

   Test the PTO Speed Sensor: Unplug the sensor (located on the back right side of the PTO housing) and check its resistance with an ohm meter. A healthy sensor should read between 2700 and 3300 ohms. Check the face of the sensor for physical scoring.

3. 3

   Test the PTO Solenoid: The PTO on/off solenoid should test at approximately 10 ohms.

1. 1

   Remove the Old Sensor

   Locate the PTO speed sensor on the PTO housing. Be prepared with a catch pan, as oil will pour out of the sensor hole when it is removed.

2. 2

   Prepare the New Sensor

   Remove the factory O-ring from the new sensor and use Teflon thread tape instead. The factory O-ring can sometimes hold the sensor out a few thousandths of an inch too far, causing an excessive air gap and inconsistent readings.

3. 3

   Install and Torque

   Thread the new sensor into the housing and torque it to 20 ft/lbs (Note: Magnum service manuals specify 12-16 lb-ft / 16-22 Nm for certain heavy-duty models, but ensure it is tightened sufficiently to avoid false slippage readings).

4. 4

   Calibrate / Configure the PTO

   Anytime the PTO speed sensor or alternator is replaced, the PTO controller must be synced. With the key and PTO turned OFF, install the configuration jumper wire at the fuse panel. Start the engine and set the RPMs to exactly 1000 (+/- 50). Move the PTO switch or lever to the RUN position. The PTO lamp will stop flashing and stay solid, indicating the computer has successfully learned the 1000 RPM baseline signal.