HOLDEN GEN III V8, Обучение по обслуживанию

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GEN III V8 ENGINE MANAGEMENT
ENGINE COOLING FANS
The PCM determines operation of the two speed
engine cooling fans based on A/C request, A/C
system pressure, engine coolant temperature and
vehicle speed signal inputs. Each engine cooling
fan motor has four terminals, two negative and two
positive terminals. The two negative terminals are
the relay controlled circuits for the fan operation.
The two positive terminals are the direct power
feed from a fusible link to the fan motors. When an
earth signal is applied to one of the negative
terminals, the fan motors will operate at low speed.
When an earth signal is applied to both negative
terminals, both fan will operate at high speed. The
engine cooling fan high speed relay is controlled by
the PCM. The PCM controls the earth path for the
engine cooling fan high speed relay. Cooling fan
low speed is controlled by the PCM via the PIM
and serial data bus to the BCM.
The BCM controls the earth path for the engine cooling fan low speed relay. The engine cooling fan high speed
and the engine cooling fan low speed relays are used to control the earth signal to the electric motors that drive
the fans. The PCM determines operation of the two, two speed engine cooling fans based on A/C request,
engine coolant temperature, A/C refrigerant pressure sensor and vehicle speed signal inputs.
ENGINE COOLING FAN LOW SPEED
The engine cooling fan low speed relay is energised by the BCM.
The cooling fan low speed relay will be turned ON when:
• The A/C request indicated (YES) and either:
• the vehicle speed is less than 30 km/h.
or
• A/C pressure is greater than 1500 kPa
or
• The coolant temperature is greater than 98°C.
• or
• If the coolant temperature is greater than 113°C, when the ignition is switched off, the relay is energised for
approximately four minutes, this is known as Low Fan Run On.
• or
• If an engine coolant temperature sensor fault is detected and a DTC such as DTC P0177, P0188, P 0 1 1 1 4
or P01115 is set.
The cooling fan low speed relay will be turned OFF when any of the following conditions have been met:
• An A/C request is not indicated (NO) and the coolant temperature is less than 95°C.
• or
• An A/C request is indicated (YES) and the vehicle speed is greater than 50 km/h and A/C pressure is less
than 1 1 7 0 kPa and the coolant temperature is less than 98°C.
ENGINE COOLING FAN HIGH SPEED
• The engine cooling fan high speed relay is controlled by the PCM. The PCM will only turn ON' the engine
cooling fan high speed relay fan if the engine cooling fan low speed relay has been "ON" for two seconds
and the following conditions are satisfied.
• There is a BCM message response fault which will cause a PIM DTC B2002.
• An engine coolant temperature sensor fault is detected and a DTC such as DTC P0177, P0188, P 0 1 1 1 4 or
P 0 1 1 1 5 is set.
• Coolant temperature greater than 108°C.
• The A/C refrigerant pressure is greater than 2400 kPa.
If the low speed fan was OFF when the criteria was met to turn the high speed fan ON, the high speed fan will
come ON 5 seconds after the low speed fan is turned ON. If both the engine cooling fan relays are ON, the
PCM will turn OFF the high speed relay when:
• The engine coolant temperature is less than 102°C.
• A/C request not indicated (NO).
• A/C request indicated (YES) and A/C pressure is less than 1900 kPa.
Note: All cooling fans will be turned off in the vehicle speed is greater than 104 kph.
GEN III V8 ENGINE MANAGEMENT Page • 73