Chart C-12A Coolant Fan Functional Check

Chart C-12A.:

A/C Circuit:

CIRCUIT DESCRIPTION:
Power for the coolant fan motor comes through the fusible link to terminal "A" on the relay. The relay is energized when current flows to ground through the quad driver module inside the ECM.

Coolant fan Relay - The coolant fan relay is energized by the ECM. The ECM energizes the relay through terminal "YE8" when the coolant temperature reaches 100°C (212°F). The fan relay is also energized when A/C is requested.

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

1. The scanner output tests allows manual control of the cooling fan.

2. Fan should be "ON" when A/C is requested at idle.

3. Ensures that the ECM is receiving an A/C request.