Yale 522752-4 – Engine Control Unit (ECU): CAM Loss (Crank Pulse without CAM Pulse)

This fault code indicates a loss of synchronization data between the engine's crankshaft and camshaft. The control module is successfully receiving a pulse/signal from the Crankshaft Position Sensor, but the corresponding pulse from the Camshaft Position Sensor is missing.

• Yale and Hyster Forklifts
• Yale VX series
• Hyster FT series
• Yale GLC models
• Yale GLP models

1. 1

   Inspect the camshaft sensor housing for dust, dirt, or metallic debris that could be blocking the magnetic pickup

2. 2

   Verify timing belt or chain tension, as a loose belt can cause the camshaft to fall out of sync with the crankshaft

3. 3

   Check for an open circuit on the sensor ground or sensor supply voltage

4. 4

   Check for an open or shorted circuit on the sensor signal wire (short to ground or short to battery)

5. 5

   If wiring, tension, and sensor are verified, check for a functional failure within the ECU

1. 1

   Disconnect the Battery

   Always disconnect the negative battery terminal before working on engine sensors or the ECU.

2. 2

   Inspect and Clean

   Locate the Camshaft Position Sensor (usually located on the cylinder head near the camshaft or integrated into the distributor on older Mazda engines). Remove the sensor and clean the mounting area and sensor tip of any debris.

3. 3

   Test the Harness

   Using a multimeter, probe the sensor connector to ensure it is receiving the correct reference voltage and has a solid ground. Check the continuity of the signal wire back to the ECU pinout.

4. 4

   Check Mechanical Timing

   Inspect the timing belt/chain. If it is loose, adjust the tensioner to the proper specification. If it has jumped a tooth, the engine must be re-timed.

5. 5

   Replace the Sensor

   If the wiring and mechanical timing are correct, the Camshaft Position Sensor has likely failed internally. Remove the retaining bolt, pull the old sensor, lubricate the O-ring on the new sensor, and install it. (Note: It is highly recommended by technicians to replace the Crankshaft Position Sensor at the same time, as they wear at similar rates).

6. 6

   Clear Codes

   Reconnect the battery, turn the ignition on, and use the dash display or Yale Axcess diagnostic tool to clear the stored fault codes. Test run the engine to ensure the code does not return.