Case IH 19891 – VCM (Vehicle Control Module) or EDC (Electronic Diesel Control) / DCU (Dosing Control Unit): Vehicle speed is too low

This fault code indicates that the control module is reading a vehicle speed that is implausibly low or non-existent compared to other operating parameters (such as engine RPM, transmission gear selection, and cardan/driveshaft speed). It typically points to a failure of the Vehicle Speed Sensor (VSS), a wiring issue, or a loss of the CAN bus message broadcasting the vehicle speed.

• Tier 4b
• Tier 4a
• Tier 4 Final
• Case N-Series Tractor Loader Backhoes (TLBs)
• 580N
• 580SN
• 580SN WT
• 590SN

1. 1

   Check for related CAN communication codes (e.g., 19889 or 19892) which indicate a CAN bus failure rather than a sensor issue.

2. 2

   Visually inspect the wiring harness leading to the Vehicle Speed Sensor for chafed wires, broken pins, or corrosion.

3. 3

   Connect the Electronic Service Tool (EST) and monitor the Vehicle Speed Sensor frequency output (should be 0–15 kHz when in motion).

4. 4

   Verify that the CAN High circuit is operating at the correct voltage (greater than 2.5 VDC).

1. 1

   Secure the Machine

   Park the machine on level ground, engage the parking brake, and turn off the engine.

2. 2

   Locate the Sensor

   Locate the Vehicle Speed Sensor, which is typically mounted on the transmission output shaft housing or the front/rear axle housing depending on the 2WD/4WD configuration.

3. 3

   Inspect and Clean

   Disconnect the VSS connector. Clean the contacts with electrical contact cleaner. Check for moisture or dirt intrusion.

4. 4

   Test the Circuit

   Using a multimeter, verify that the sensor is receiving proper ground and signal reference voltage from the VCM (referencing pins such as VCM Pin 15 or 21/22 depending on the exact model's schematic).

5. 5

   Replace the Sensor

   If the wiring is intact and the EST confirms no frequency signal is being generated while the output shaft is spinning, the sensor has failed internally. Unbolt the retaining bolt, pull the old sensor out, lubricate the O-ring on the new sensor with clean transmission fluid, and install it.

6. 6

   Clear and Verify

   Reconnect the harness, clear the fault codes using the EST, and perform a test drive to verify the speedometer registers correctly and the code does not return.