Lift truck diagnostics

Abstract

The present invention features a diagnostic method for assessing intermittent failures which occur in the components and systems of material handling vehicles. The material handling vehicle of this invention uses an on-board microprocessor and display to allow an operator to determine whether any intermittency is present in the internal systems. The microprocessor is programmed to analyze each system during normal vehicular operation. The program is divided into two vehicular modes, 'normal operating' and 'program'. During the normal operating mode, the vehicle operator is warned of a problem by different audible tones and patterns. A fault code scrolls across the vehicle display screen, indicating the nature of the failure. The program mode can then be entered to assess just where the problem is located. The program mode is divided into three additional modes: 'maintenance mode', 'configure mode' and 'learn mode'. The vehicle is selected for maintenance diagnostics during the program mode, and then switched back to the normal operating mode, where the intermittent failures can be diagnosed. The maintenance mode is divided into three diagnostic surveys: output controls, digital input measurements for analyzing switches and encoders, and analog input measurements for testing voltages and potentiometers. Each system in the vehicle can be analyzed by selecting the proper maintenance code.