Chart C-9A Early Fuel Evaporative (EFE) Heater Check

Diagnostic Chart:

Early Fuel Evaporative Heater Circuit:

CIRCUIT DESCRIPTION
The Early Fuel Evaporation (EFE) heater provides a source of rapid heat to the air/fuel mixture during cold start conditions. Rapid heating provides quick fuel evaporation, a more uniform fuel distribution and also reduces the length of time the engine is in "Open Loop," reducing the exhaust emission levels. When the Engine Control Module (ECM) determines that the engine coolant temperature is below operating temperature and the engine speed is above idle, it will energize the Positive Temperature Coefficient (PTC) heater relay coil. Voltage will then be applied to the EFE heater through the PTC heater relay contacts. When the engine reaches operating temperature, or the engine speed is reduced to idle, the ECM will de-energize the EFE system.

CHART TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. This checks for an open in YEL/RED wire between PTC heater relay and ECM or for a faulty ECM.
2. This checks for an open in WHT/BLU wire between PTC heater relay and MAIN relay.
3. This checks for an open in WHT wire between PTC heater relay and fuse box or for a faulty PTC heater relay.
4. This checks for a faulty WHT/BLK or BLK wire or for a faulty EFE heater.

DIAGNOSTIC AIDS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.