Page 122 of 502

07-6
RODIUS 2005.07
2110-01
ENGINE COOLING SYSTEM
2. DESCRIPTION AND OPERATION
1) GENERAL DESCRIPTION
The cooling system maintains the engine temperature at an efficient level during all engine
operating conditions. When the engine is cold, the cooling system cools the engine slowly o
r
not at all. This slow cooling of the engine allows the engine to warm up quickly.
The cooling system includes a radiator and recovery subsystem, cooling fans, a thermostat and
housing, a water pump, and a water pump drive belt. The timing belt drives the water pump.
All components must function properly for the cooling system to operation. The water pump
draws the coolant from the radiator. The coolant then circulates through water jackets in the
engine block, the intake manifold, and the cylinder head. When the coolant reaches the
operating
temperature of the thermostat, the thermostat opens. The coolant then goes back to the
radiator where it cools.
This system directs some coolant through the hoses to the heat core. This provides for heating
and defrosting. The coolant reservoir is connected to the radiator to recover the coolant
displaced by expansion from the high temperatures. The coolant reservoir maintains the correct
coolant level.
The cooling system for this vehicle has no radiator cap or filler neck. The coolant is added to
the cooling system through the coolant reservoir.
2) RADIATOR
This vehicle has a lightweight tube-and-fin aluminum radiator. Plastic tanks are mounted on the
upper and the lower sides of the radiator core.
On vehicles equipped with automatic transaxles, the transaxle fluid cooler lines run through the
radiator tank. A radiator drain plug is on this radiator.
To drain the cooling system, open the drain plug.
Page 124 of 502

07-8
RODIUS 2005.07
2110-01
ENGINE COOLING SYSTEM
5) WATER PUMP
The belt-driven centrifugal water pump consists of an impeller, a drive shaft, and a belt pulley.
The impeller is supported by a completely sealed bearing.
The water pump is serviced as an assembly and, therefore, cannot be disassembled.
6) ELECTRIC COOLING FAN
Keep hands, tools, and clothing away from the engine cooling fans to help prevent
personal injury. This fan is electric and can turn on even when the engine is not running. -
f a fan blade is bent or damaged in any way, no attempt should be made to repair or reuse
the damaged part.
A bent or damaged fan assembly should always be replaced with a new one to prevent
possible injury. -
The cooling fans are mounted behind the radiator in the engine compartment. The electric
cooling fans increase the flow of air across the radiator fins and across the condenser on ai
r
conditioned (A/C)-equipped vehicles.
This helps to speed cooling when the vehicle is at idle or moving at low speeds.
All models have two fans. The main fan is 320 mm (12.6 inches) in diameter with seven blades
to aid the airflow through the radiator and the condenser. An electric motor attached to the
radiator support drives the fan. The auxiliary fan is 320 mm (12.6 inches) in diameter.
7) A/C OFF OR NON-AC MODEL
The cooling fans are actuated by the engine control module (ECM) using a low-speed
cooling fan relay, a high-speed cooling fan relay and a cooling fan motor relay.
The ECM will turn the cooling fans on at low speed when the coolant temperature reaches
95°C (203°F) and at high speed when the coolant temperature reaches 105°C (221°F).
The ECM will change the cooling fans from high peed to low speed at 100°C (212°F)
and will turn the cooling fans off at 90°C (194°F). ·
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Page 363 of 502
0-11
CLUSTER
RODIUS 2005.07
8010-10
4) Coolant Temperature Gauge
The coolant temperature gauge displays the coolant temperature with a pointer. The angle of
pointer that changes by coolant temperature is as shown below.
Measurement of coolant temperature sensor resistance
Measure the resistance between the terminal and the ground with an ohmmeter and replace i
f
the resistance is out of specified range.
Resistance value by coolant temperature:
20°C : 2449 Ω ±5 %
50°C : 826 Ω ±5 %
80°C : 321 Ω ±5 %
100°C : 112 Ω ±5 %
When the resistance value by coolant temperature is within the specified range, check
thermostat, water pump, radiator related coolant circuit for normal operation. Also, check the
wiring harnesses and connectors for proper connection.
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