The manifold heater's purpose in life is to heat the
fuel mixture to aid vaporization when the engine is
started at temperatures below 160° F. It replaces the
common exhaust manifold heat riser valve. The heater
itself is in the intake manifold under the carburetor.
What is pictured here is
the thermal switch that operates it. The switch is in the
intake manifold's water jacket toward the rear. The green
wire goes to a
relay that is taped
to the main wiring harness against the firewall. The red
wire you see goes from the relay back to the heater. You
should find 12 volts at this red wire, but only while the
engine is warming up. The resistance between the red wire
and ground is around 1 ohm, making the heater roughly a
200 watt unit.
This heater is independent of the
computer, and is not controlled by it.
