From argyll in Lockport,NY. Just purchased a 2015 3540pst. Trying to find out why the intake manifold heater light will not stay on. Tested the 60amp fuse and 1 inch square relay ,[no timer built in relay] and they tested good. wiring diagram does not show another relay in the circuit. Do they rely on the thermostat on the heater coil as the timer? Should I check the heater coil itself? Ordred a service and parts manual, but thought I would ask the forum to get a jump start on fixing it.