Yale 190-4 – Engine Control Unit (ECU) or Vehicle System Manager (VSM): Crank Loss (CAM Pulse without Crank Pulse)

The control module is receiving a rotational signal from the Camshaft Position Sensor (CAM pulse) but is not receiving a corresponding signal from the Crankshaft Position Sensor (Crank pulse). This means the engine is turning, but the system has lost the crankshaft position data required for proper fuel injection and ignition timing.

• Yale and Hyster Forklifts
• 2005 and newer models
• VX Series
• GC040-070VX
• GLC020-070VX
• GDP20-35VX

1. 1

   Check for dust, dirt, or debris packed into the crankshaft sensor housing that could block the magnetic signal

2. 2

   Verify that the timing belt is tensioned properly and has not jumped a tooth, which can cause synchronization loss

3. 3

   Check the sensor circuit for an open ground or an open power supply wire

4. 4

   Check the sensor signal wires for an open circuit or a short circuit (short to ground or short to battery)

5. 5

   Rule out a functional failure within the ECU/VSM itself

1. 1

   Clean the Sensor Area

   Locate the crankshaft position sensor. Remove it and clean the sensor tip and the housing of any accumulated dust or metallic debris. Reinstall and test.

2. 2

   Inspect the Timing Belt

   Access the timing belt cover and verify that the belt is tight and the mechanical timing marks align perfectly. Adjust tension if necessary.

3. 3

   Test the Wiring

   Disconnect the crankshaft position sensor. Using a multimeter, verify that the sensor connector is receiving the correct reference voltage and has a solid ground. Check the continuity of the signal wire back to the ECU/VSM pinout to ensure there are no breaks or shorts in the harness.

4. 4

   Replace the Sensor

   If the wiring is intact, the timing is correct, and the housing is clean, the sensor itself has likely failed internally. Replace the Crankshaft Position Sensor.

5. 5

   Clear Codes and Test

   Clear the fault codes from the dash/VSM and operate the forklift to ensure the 190-4 code does not return. If it does, the ECU/VSM may require replacement or reprogramming.