Chevrolet Sonic Repair Manual: Cooling Fan Description and Operation (LUV)
The engine cooling fan system is composed of one cooling fan, a series of 5 relays, the engine control module (ECM), and the associated wiring. The cooling fan assembly includes two resistors. This combination of components enables the ECM to operate the cooling fan at 3 speeds using two fan control circuits.
Low Speed Operation
The ECM applies ground at the FAN 1 control circuit for the coil side of the cooling fan relay. The energized cooling fan relay completes a ground, through the switch side of the relay, for the coils of the cooling fan low speed relay and the cooling fan speed control relay. The speed control relay activates and supplies B+ to the coil side of the cooling fan high speed relay. The high speed relay remains inactive because the ECM is not commanding the FAN 2 control circuit ON. The energized low speed relay switch closes to supply B+ through the internal low speed resistor of the engine cooling fan motor. The result is cooling fan operation at a reduced speed.
Medium Speed Operation
The ECM applies ground at the FAN 2 control circuit for the coil side of the cooling fan high speed, and medium speed relays. The high speed relay remains inactive because the ECM is not commanding the FAN 1 control circuit ON. The energized medium speed relay switch closes to supply B+ through the internal medium speed resistor of the engine cooling fan motor. The result is cooling fan operation at a medium speed.
High Speed Operation
The ECM applies ground at the FAN 1 control circuit for the coil side of the cooling fan relay. The energized cooling fan relay completes a ground, through the switch side of the relay, for the coil of the cooling fan speed control relay. The energized speed control relay switch closes to supply B+ to the coil side of cooling fan high speed relay. Simultaneously, the ECM applies ground at the FAN 2 control circuit for the coil side of the cooling fan high speed relay. The energized high speed relay switch closes to supply B+ directly to the engine cooling fan motor, by-passing the fans internal resistors. The result is cooling fan operation at full speed.
Radiator Fan
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Cooling Fan Description and Operation (LWE, LUW)
System Overview
The engine cooling fan system is composed of one cooling fan, 2 relays, the engine
control module (ECM), and the associated wiring. The cooling fan assembly includes
1̴ ...
Other materials:
Trunk (Sedan)
Warning
Exhaust gases can enter the vehicle if it is driven with the liftgate, hatch/trunk
open, or with any objects that pass through the seal between the body and the hatch/trunk
or liftgate. Engine exhaust contains carbon monoxide (CO) which cannot be seen or
smelled. It can cause unconsci ...
Tire and Wheel Assembly Balancing - On-Vehicle
Special Tools
EL-38792-A Electronic Vibration Analyzer (EVA) 2
If after following the tire and wheel vibration diagnostic process, some amount
of tire and wheel vibration is still evident, an on-vehicle high-speed spin balancer
may be used to perform an on-vehicle balance in an attempt ...
Evaporative Emission Canister Replacement (Steel Tank)
Removal Procedure
Remove the evaporative emission canister bracket fasteners (1).
Disconnect the purge solenoid valve electrical connector (1).
Disconnect the evaporative emission canister vent hose (2).
Disconnect the evaporative emission c ...
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