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
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Other materials:
Door Lock and Ignition Lock Folding Key Blade Removal and Installation
Special Tools
BO-51098 Flip Key Blade Fixture
For equivalent region tools, refer to Special Tools.
Caution: Failure to properly support the Remote Keyless Entry
(RKE) transmitter assembly while replacing the key blade may cause internal
damage to the transmitter assembly. ...
Replacing Safety Belt System Parts after a Crash
Warning: A crash can damage the safety belt system in the vehicle.
A damaged safety belt system may not properly protect the person using it, resulting
in serious injury or even death in a crash. To help make sure the safety belt
systems are working properly after a crash, have them insp ...
SIR Identification Views
The SIR Identification Views shown below illustrate the approximate location
of all SIR components available for the vehicle. This will assist in determining
the appropriate SIR Disabling and Enabling for a given service procedure, refer
to SIR Disabling and Enabling.
Supplemental Inf ...
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