REL.HEAT LOW ________________________________________________ (range YES/NO) Indicates whether the coolant or air temperature is above or below the set temperatures and is used by the glow plug start system. RELAY HEATER HIGH RELAY HEATER LOW ___________________________________________ (range ON/OFF) Indicates the current output state of the glow plug start system relay circuits. SLIDE VALVE SENSOR(V) Indicates the voltage of the modulating piston replacement sensor. Part of the Injection Pump, the Quantity adjuster regulates the quantity of fuel injected an electromagnetic swivelling positioner, ECM duty cycle controlled. The rotational angle of an eccentric shaft attached to the quantity adjuster is measured by the modulating piston displacement sensor (slide valve sensor) The sensor variable voltage directly correlates to how much fuel is delivered. Normal range is 1.45 to 2.0 V. Below 1.450 V, mixture is too rich Above 2.0 V, mixture is too lean. Slide Valve Sensor Min. V range is 0.500 to 0.970 V. Slide Valve Sensor Max V range is 4.150 to 4.740 V.