DTC P0481: Cooling Fan No. 2 & 3 Relays Control Circuit: Description

Battery positive voltage is supplied to cooling fan No. 2 and 3 relay from cool fan fuse. Powertrain Control Module (PCM) controls relays by grounding high speed cooling fan relay control circuit via a driver. The primary function of the driver is to supply ground for component being controlled. Each driver has a fault line which is monitored by PCM. When PCM is commanding a component on, voltage potential of the control circuit should be low (near zero volts). When PCM is commanding the control circuit to a component off, voltage potential of circuit should be high (near battery voltage). PCM will monitor control circuit for short to ground, short to voltage or an open.