Join Date: Nov 2000
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Re: Manifold Heater Question
I just wired mine back in this morning. There is a heavy red wire, about 10 gauge that goes to battery (actually it runs to the connector on the wirewall, drivers side and gets battery power, ie always live). There is a thin red /white stripe wire that goes to key on power. That powers the relay. There is a green wire that goes to the sensor on the intake manifold, and provides ground, thus closing the relay, until the motor heats up, and an orange wire that goes to the heater element. The heater element is self grounded thru the intake manifold and bolts.
If all works as planned, turning on the key with a cold engine will close the relay via low current running from the thin red wire, thru the relay coil, out to ground by the green wire thru the temperature activated switch. This circuit controls and closes the relay when the engine is cold. The closed relay then provides high current (say 20 amps) through the closed relay contacts to the orange wire that powers the heater element. If you want to test the element, see that it will draw current when hooked to the battery by a 10 gauge wire. If you find the element good, and that it improves cold running, you will need to wire up a relay to handle the current draw and turn it off once the engine coolant gets up to temperature. It's a black topped sensor with a single round lug on top located on the top surface of the intake manifold that controls it, as mentioned earlier, by providing a path to ground when it is cold.
I tested the element on the bench, and in 20 seconds it gets very hot, in 60 seconds the whole assembly is too hot to touch.