GM Service Manual Online
For 1990-2009 cars only

Powertrain Control Module (PCM) or Engine Control Module (ECM) Scan Tool Output Controls LX9/LZ9 3.5L/3.9L only

Scan Tool Output Control

Additional Menu Selection(s)

Description

Fans Low Speed

Fan Relays

The scan tool displays a Commanded State of Off or On. This allows you to communicate with the PCM/ECM and activate or deactivate the cooling fan 1 relay, manually turning the low speed fans On and Off.

Fans High Speed

Fan Relays

The scan tool displays a Commanded State of Off or On. This allows you to communicate with the PCM/ECM to activate or deactivate the cooling fan 1 relay, manually turning the low speed fans On. After a 3 second delay the PCM/ECM will activate the cooling fan S/P relay and the cooling fan 2 relay. This turns the high speed fans On and Off.