Cooling Fan Control

WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.

The engine cooling fan system consists of 2 cooling fans and 3 relays. The relays are powered by the battery positive voltage circuit and controlled by a switched ground from the powertrain control module (PCM).

During low speed operation, the PCM supplies the ground path for the low speed cooling fan relay through the low speed cooling fan relay control circuit. This energizes the cooling fan low relay coil, closes the relay contacts, and supplies battery positive voltage from the COOL FAN LO fuse through the cooling fan motor supply voltage circuit to the cooling fan. During high speed operation the PCM supplies the ground path for the cooling fan low relay through the low speed cooling fan relay control circuit. After a 3-second delay, the PCM supplies a ground path for the cooling fan high relay and the s/p cooling fan relay through the high speed fan relay control circuit.

The PCM commands the fan on under the following conditions:

Engine coolant temperature exceeds approximately 98°C (208°F) Low Fan Speed
Engine coolant temperature exceeds approximately 102°C (216°F) High Fan Speed
A/C refrigerant pressure exceeds 361 kPa (52 psi) Low Fan Speed
A/C refrigerant pressure exceeds 2100 kPa (300 psi) High Fan Speed
When the engine coolant temperature exceeds 112°C (234°F) at key off, the fan high speed will run for up to 300 seconds. If within that time frame 102°C (216°F) is reached then fan speed will change from high to low speed. If within that time frame 99°C (210°F) is reached then fan speed will change from low to off.

The PCM commands the fan off under the following conditions:

A/C is requested and engine speed exceeds 6,240 RPM
Engine coolant temperature exceeds approximately 99°C (210°F) turns the cooling fans from low to off.