GM Service Manual Online
For 1990-2009 cars only

Engine Control Module (ECM)

Scan Tool Output Control

Additional Menu Selection(s)

Description

Fan Relay 1

Special Functions/Output Control/Cooling Fan

The scan tool displays a Commanded State of None, OFF or ON. This allows you to communicate with the ECM and activate or deactivate the cooling fan 1 relay, manually turning both cooling fans ON and OFF at low speed.

Fan Relays 2 and 3

Special Functions/Output Control/Cooling Fan

The scan tool displays a commanded state of None, OFF or ON. This allows you to communicate with the ECM to activate or deactivate the cooling fan 2 relay and the cooling fan series parallel (S/P) relay. This commands one of the cooling fans ON at high speed.

Fan Relays 1, 2 and 3

Special Functions/Output Control/Cooling Fan

The scan tool displays a Commanded State of None, OFF or ON. This allows you to communicate with the ECM to activate or deactivate the cooling fan 1 relay, manually turning the low speed fans On. After a 3 second delay the ECM will activate the cooling fan S/P relay and the cooling fan 2 relay. This commands both cooling fans ON at high speed.