Chart C-9D, EFE Circuit Check
When the engine is cold, heater switch is closed, allowing current to flow to grid with ignition on. When heater switch reaches its calibrated value, the switch opens the circuit, stopping current flow to the grid.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- Backprobing the heater switch checks for voltage to the switch and checks switch continuity.
- This tests wiring between heater switch and grid connector.
- This tests heater grid ground connection.
- If grid resistance measures over 3 ohms, grid will not heat up sufficiently and should be replaced.
- This tests to see if heater switch is opening when engine warms up.