PINPOINT TEST KF: Fan Control (FC) Relays: Introduction

WARNING: This page does not describe the selected car, but rather 31 other vehicles, including the 2008 Mercury Sable, 2008 Mercury Mountaineer, 2008 Mercury Milan, 2008 Mercury Mariner, and 2008 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.

This pinpoint test is intended to diagnose the following:

LFC, MFC, HFC relays
harness circuits: HFC, LFC, MFC, VPWR
powertrain control module (PCM) (12A650)

Although the PCM output circuits are called low, medium and high fan control (FC), cooling fan operation is controlled by a combination of these outputs.

Refer toENGINE CONTROL COMPONENTS .

Fig 1: Low Fan Control (LFC) Relay Connector

Courtesy of FORD MOTOR CO.

Pin	Circuit
2	LFC (Low Fan Control)
1	VPWR (Vehicle Power)

NOTE: The VPWR and LFC circuits may be reversed in the harness connector. Also, the LFC circuit may be wired to 2 separate relays. Refer to the Wiring Diagrams article for additional information.

Fig 2: Medium Fan Control (MFC) Relay Connector

Courtesy of FORD MOTOR CO.

Pin	Circuit
2	MFC (Medium Fan Control)
1	VPWR (Vehicle Power)

NOTE: The VPWR and MFC circuits may be reversed in the harness connector. Also, the MFC circuit may be wired to 2 separate relays. Refer to the Wiring Diagrams article for additional information.

Fig 3: High Fan Control (HFC) Relay Connector

Courtesy of FORD MOTOR CO.

Pin	Circuit
2	HFC (High Fan Control)
1	VPWR (Vehicle Power)

NOTE: The VPWR and HFC circuits may be reversed in the harness connector. Also, the HFC circuit may be wired to 2 separate relays. Refer to the Wiring Diagrams article for additional information.

For PCM connector views or reference values, refer to the REFERENCE VALUES article.

Vehicle	Pin	Circuit
Escape/Mariner 2.3L	B38 B17 B39	HFC MFC LFC
Focus	B18 B34	HFC LFC
Mustang	E4 E7	HFC LFC
Ranger	E7	LFC
All other vehicles	B38 B39	HFC LFC