A logistics warehouse reported a safety-critical issue: a Hyster N45DR reach truck would suddenly lose all drive and hydraulic power while driving. The operator had to rock the seat or cycle the key to get it back. This is a "Deadman" safety system fault.
The N45DR uses a "Sense-A-Seat" system. A pressure sensor under the seat cushion detects if an operator is present. If the sensor loses the signal, the machine shuts down. The technician checked the sensor calibration. The weight threshold was set too high. When the operator shifted their weight to look behind, the pressure momentarily dropped below the threshold, triggering a shutdown. He recalibrated the seat sensor to a lower threshold.
However, the fault returned. The technician then inspected the CAN bus communication. He found that the error code coincided with a "Accelerator Pedal Signal Loss." He traced the wiring harness from the accelerator pedal to the controller. Under the floor plate, the harness connector was corroded due to a leak in the floor mat seal (driver spilled water). The green mold on the pins caused intermittent contact.
The repair involved drying the connector, cleaning the pins with contact cleaner, and applying dielectric grease. The floor mat was resealed to prevent moisture ingress. The seat sensor was recalibrated to the operator's weight range. The intermittent shutdowns ceased, and the reach truck operated reliably.
