Exhaust Heat Recirculation System Circuit

2GR-FXE COOLING: EXHAUST HEAT RECIRCULATION SYSTEM: Exhaust Heat Recirculation System Circuit
- Exhaust Heat Recirculation System Circuit

DESCRIPTION

In the exhaust heat recirculation system, coolant is warmed up using exhaust gas heat to decrease engine warm-up time, enhancing fuel efficiency and heater performance. This system allows the engine to be warmed up with efficiency, contributing to low fuel consumption.

The heat recirculator is positioned in the center exhaust pipe assembly after the catalyst. Coolant from the engine flows around the heat recirculator and then returns to the engine. If the engine is started while the engine is cold, the exhaust pipe gas control actuator rod is contracted and the exhaust flow control valve is closed, routing the exhaust gas around the heat recirculator to warm up the coolant.

After the engine coolant temperature rises and the engine has warmed up, the heat of the coolant expands the thermostat and the exhaust pipe gas control actuator rod extends. This opens the exhaust flow control valve to switch to the normal exhaust gas path.

The exhaust flow control valve can also be opened by exhaust gas pressure to prevent insufficient acceleration performance when the engine is cold. In addition, to monitor the engine coolant temperature, a water temperature switch is installed between the engine and heat recirculator. When the engine coolant temperature is normal, the water temperature switch is closed (on). If the engine coolant temperature is excessively high (overheating), the switch opens (off) and the needle of the water temperature receiver gauge in the combination meter assembly indicates above HI to inform the driver of the malfunction.





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WIRING DIAGRAM

Refer to System Diagram Description and Operation.

INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (TEMPERATURE SWITCH - COMBINATION METER ASSEMBLY)

(a) Disconnect the temperature switch connector.





(b) Disconnect the combination meter assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





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(d) Reconnect the combination meter assembly connector.

(e) Reconnect the temperature switch connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (TEMPERATURE SWITCH - COMBINATION METER ASSEMBLY)
OK -- Continue to next step.

2. CHECK COMBINATION METER ASSEMBLY

(a) Disconnect the temperature switch connector.

(b) Turn the ignition switch to ON.

(c) Check the water temperature receiver gauge in the combination meter assembly.

Result:





(d) Reconnect the temperature switch connector.

B -- REPLACE COMBINATION METER ASSEMBLY Removal

A -- REPLACE TEMPERATURE SWITCH Removal