The grid heater is between the intake elbow and the intake manifold. It’s just a big resistor that heats up when current is applied across it and thus heats the incoming air charge until cylinder and engine temps get up to operating temperature.

How do I know if my grid heater is working?

If the grid heater is working you should be able to feel heat around the base of the intake pipe connected to the head. You should check the ground connection at the grid heater. Also trace the grid heater wiring back to the solenoids and make sure they are all tight with no corrosion.

What is an intake grid heater?

Air Intake Heaters, also known as grid and manifold heaters, provide solutions for diesel applications such as On-Highway, Off-Road and Power Generation. Powered by the vehicle battery, air intake heaters provide an on-board, stand-alone cold weather starting aid without driver intervention.