John Deere PTI000191.02 – PTI: Speed Difference Exceeds 200 RPM

The Power Train Control Unit (PTI) has detected a speed difference of more than 200 rpm between rotational speed signals from various speed sensors. This mismatch, often occurring between different wheels or between the wheel speed and transmission output speed, indicates conflicting speed data. It is typically caused by mismatched tire sizes, faulty wheel speed sensors, or damaged sensor wiring on tractors equipped with Infinitely Variable Transmissions (IVT) or AutoPowr transmissions.

• 5E
• 6D
• 6M
• 6R
• 7M
• 7R
• 8R
• 8RT

1. 1

   Return the shift lever to Park and restart the engine to attempt a basic system recovery

2. 2

   Verify that front and rear tires are the correct size and combination for the tractor model, and ensure all tires are inflated to the recommended pressure (mismatched sizes cause conflicting speed reports)

3. 3

   Visually inspect the wheel speed sensors (located on the transmission or final drive housing) and their wiring harnesses for physical damage, dirt buildup, or loose connections

4. 4

   Check electrical connectors at the speed sensors and the PTI control unit for cleanliness, security, and corrosion

5. 5

   Perform a resistance test on the wheel speed sensor using a multimeter and compare the reading to manufacturer specifications or a known good sensor

6. 6

   Perform an AC voltage output test on passive sensors by back-probing the connector, spinning the raised wheel by hand, and verifying that AC voltage increases with wheel speed

1. 1

   Address non-sensor issues

   If incorrect tire sizes or pressures were identified, correct these issues first. Clear the fault codes and operate the machine to see if the code returns.

2. 2

   Clean and secure connections

   If dirt or loose connections were found during inspection, clean the sensor and its connector, ensure a secure connection, clear the codes, and re-test.

3. 3

   Replace wheel speed sensor

   If a sensor is determined to be faulty, remove its single retaining bolt on the transmission or axle housing and pull it out (be prepared for a small oil leak). Install the new sensor, tighten the bolt, and securely connect the wiring harness.

4. 4

   Calibrate new wheel speed sensor

   Measure a 122-meter (400-foot) course on flat terrain. Access the 'Wheel Speed Sensor Calibration' menu on the machine's display (e.g., CommandCenter). Drive the course as prompted, perform the run three times to average the results, and enter the new average calibration value into the control unit.

5. 5

   Clear codes and test

   After repair and calibration, clear all fault codes from the PTI controller and operate the tractor under various conditions to ensure the fault does not return.