Just the solenoids were replaced. The grid heaters worked still. With the use of a multi-meter, we were able to diagnose the solenoid that was constantly closed, and not opening to turn the grid heater off. His intake horn is still a burnt color to this day.
There are 2 solenoids, and two heaters. Depending on the temperature, one or both will come on.
There is a schematic of the heaters. The relays are positively switched from the ECU, and have a constant ground. Hope that helps in diagnostics.