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

This pinpoint test is intended to diagnose the following:

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

Three Speed Fan Operation 

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 to ENGINE CONTROL COMPONENTS .

Fig 1: Low Fan Control (LFC) Relay Connector

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 appropriate SYSTEM WIRING DIAGRAMS article for additional information.

Fig 2: Medium Fan Control (MFC) Relay Connector

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 appropriate SYSTEM WIRING DIAGRAMS article for additional information.

Fig 3: High Fan Control (HFC) Relay Connector

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 appropriate SYSTEM WIRING DIAGRAMS article for additional information.

Powertrain Control Module (PCM) Connector 

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