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:
Cleaning High Gloss Surfaces and Vehicle Information and Radio Displays
For vehicles with high gloss surfaces or vehicle displays, use a microfiber cloth
to wipe surfaces. Before wiping the surface with the microfiber cloth, use a soft
bristle brush to remove dirt that could scratch the surface. Then use the microfiber
cloth by gently rubbing to clean. Never use w ...
Front Side Door Lock Cylinder Coding (Free Wheeling)
Special Tools
BO-49753 Assembly Tool
The door lock cylinder uses 8 of the 8 cut positions. The tumbler positions are
staggered from side to side, 4 on one side and 4 on the other, are not self-retaining,
and are not snap in.
Note: All lock cylinders for side milled keys ha ...
Engine Oil Cooler Disassemble
Remove the oil cooler coolant inlet hose clamp (2).
Remove the oil cooler coolant inlet hose (1).
Remove the oil cooler coolant inlet pipe bolt (7)
Remove the oil cooler coolant inlet pipe (3) and the seal ring (6).
Remove the oil cooler coolant out ...
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