Function
To inform the operator of various machine operating conditions as well as controlling certain lighting operations. The display panel provides the logic to operate the various machine safety interlocks in addition to offering limited diagnostic functions.
Operating Conditions
Key switch in the START or RUN position
Theory of Operation – Display Panel
There are three modes of operation, key switch, hazard, and back light mode.
When the key switch is in the run position:
– Tell tale indicators are on for one second.
– The LCD display icons are activated for one second.
– The analog gauges are moved from the zero position to full deflection and return to the
operation position based on gauge inputs. This occurs within three seconds.
When the key switch is in the off position and the light switch is in the hazard position, the hazard lights operate and the hour meter is displayed.
When the key switch is in the off position and the light switch is in the on position, the LCD display backlights operate and the hour meter is displayed.
Interlock circuits are active within 0.2 seconds of key switch ON when conditions are met.
Needle sweep and light check conclude within 5 seconds. Needle sweep and light check may continue or be temporarily suspended while the Crank input is active.
Power for the module is supplied through (1) switched and (1) unswitched connection to the battery; a single point grounding wire completes the circuit.
The module turns off all outputs if the electrical system exceeds 20 volts, and selected outputs below 9 volts. This is done to prevent damage to electrical components and possible inadvertent operation.
Engine Oil Pressure Light
The engine oil pressure light is controlled by the oil pressure switch. Whenever oil pressure drops to unsafe levels, the switch contacts close and completes the ground path that illuminates the warning light. The oil pressure switch also influences hour meter logic.
Tachometer
The tachometer display is driven by pulses from the alternator while the engine is running.
An engine speed of 3000 rpm correlates to an input frequency of 465 Hz.
Engine Temperature Gauge and Indicator Light
Changes in engine coolant temperature are sensed by a variable-resistance temperature sender. The module translates that resistance value into a temperature reading. A colored scale on the temperature gauge indicates the safe (green) and unsafe (red) zones of operation.
Should engine heating become excessive (red zone), the overheat indicator light glows and stays lit until the temperature drops sufficiently to safe (green zone) levels. PTO operation is suspended for the duration of the overheat condition.
Hour Meter
The hour meter records the hours of engine operation. Time is measured to within ±5% and displayed to the nearest 0.1 hour. Accumulation of time occurs when the key is on, AND (tachometer is above 450 rpm OR [EOP Initial State is close to the previously recorded value, AND engine oil pressure input is open, AND seat switch is active]). While accumulating, the hour glass icon flashes at the rate of once per second.
Diagnostic Trouble Codes
The error codes are displayed on the LCD panel to indicate a problem on certain outputs and the reasons for not being able to turn on the fuel solenoid. The error codes will be displayed for 2 seconds every 10 seconds as long as the fault persists, except for Fuel Solenoid OFF codes. Fuel Solenoid can be OFF, if during initial power-up, PTO switch is ON or Neutral switch is OFF.
→NOTE:
Fault will have to be active for at least 0.5 seconds before the error is displayed to avoid nuisance errors.
