3.1L & 3.8L "W" Body (Grand PRIX): Description

• 3.1L
  
  Engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. Relays are arranged in series/parallel configuration that allows Powertrain Control Module (PCM) to operate both fans together at low or high speeds. Cooling fans and fan relays receive battery voltage from underhood accessory wiring junction block. During low speed operation, PCM supplies ground path for low speed fan relay through low speed cooling fan relay control circuit. This energizes cool fan 1 relay coil, closes relay contacts, and supplies battery voltage from cool fan 1 fuse through cooling fan motor supply voltage circuit to left cooling fan. Ground path for left cooling fan is through cool fan relay and right cooling fan. Result is a series circuit with both fans running at low speed. During high speed operation, PCM supplies ground path for cool fan 1 relay through low speed cooling fan relay control circuit. After a 3-second delay, PCM supplies a ground path for cool fan 2 relay and cool fan relay through high speed cooling fan relay control circuit. This energizes cool fan relay coil, closes relay contacts, and provides a ground path for left cooling fan. At same time, cool fan 2 relay coil is energized closing relay contacts and provides battery positive voltage from cool fan 2 fuse on cooling fan motor supply voltage circuit to right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.
• 3.8L
  
  Engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. Relays are arranged in a series/parallel configuration that allows Powertrain Control Module (PCM) to operate both fans together at low or high speeds. Cooling fans and fan relays receive battery voltage from underhood accessory wiring junction block. During low speed operation, PCM supplies ground path for low speed fan relay through low speed cooling fan relay control circuit. This energizes cool fan 1 relay coil, closes relay contacts, and supplies battery voltage from cool fan 1 fuse through cooling fan motor supply voltage circuit to right cooling fan. Ground path for right cooling fan is through cool fan relay and left cooling fan. Result is a series circuit with both fans running at low speed. During high speed operation PCM supplies ground path for cool fan 1 relay through low speed cooling fan relay control circuit. After 3-second delay, PCM supplies ground path for cool fan 2 relay and cool fan relay through high speed cooling fan relay control circuit. This energizes cool fan relay coil, closes relay contacts, and provides a ground path for right cooling fan. At same time cool fan 2 relay coil is energized closing relay contacts and provides battery voltage from cool fan 2 fuse on cooling fan motor supply voltage circuit to left cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. Result is a parallel circuit with both fans running at high speed.

PCM commands low speed fans on under the following conditions:

• Engine coolant temperature exceeds approximately 223°F (106°C).
• When A/C is requested and ambient temperature is greater than 122°F (50°C).
• A/C refrigerant pressure exceeds 190 psi.
• After vehicle is shut off, if engine coolant temperature at key-off is greater than 284°F (140°C) and system voltage is more than 12 volts. Fans will stay on for approximately 3 minutes.

PCM commands High Speed Fans on under the following conditions:

• Engine coolant temperature reaches 230°F (110°C).
• A/C refrigerant pressure exceeds 240 psi.
• When certain DTCs set.