Engine Electrical System

Hints: the vehicle is equipped with 2 water
temperature sensors, one is single-pin water
temperature sensor, providing the water temperature
gauge with water temperature signal; the other is
double-pin, providing the engine ECU with water
temperature signal.
Pins: this sensor has 3 pins, which can interchange for
use.
1 coolant temperature sensor signal (ECU 39#)
2 sensor signal ground (ECU 35#)
3 another line connects water temperature signal of
gauge.
Troubleshooting: mainly check if there is short circuit
or open circuit on the connection between 3 lines,
ECU and gauge on sensor.
If there is short circuit, open circuit or grounding
between sensor wire harnesses.
Line grounding or defect grounding is liable to cause
engine water temperature gauge to indicate excessive
temperature.
※Knock Sensor KS
Purpose: this sensor is designed to provide ECU with
engine knocking information so as to carry out
knocking control.
Composition and principle: knock sensor is a sort of
vibration acceleration sensor, which is fixed on engine
cylinder block. ECU controls engine ignition via
signals detected by pressure-sensing element.
Failure diagnosis:
ECU monitors on various sensors,
actuators, power amplification circuits and sensing
circuits. In case any of the following situations occurs,
failure mark of the knock sensor is set.
Knock sensor failure
Knocking control data processing circuit failure
Cylinder-detecting signal is unreliable
After failure mark of knock sensor being set, knocking
closed-loop control is shut down, reducing a safety
angle from the ignition advance angle stored in ECU.
When error frequency cuts down to below setting
KS with cable
1.K
nock
ing
block
2.Casing
3.P
iezoelectric
ceramics
4.Contactor
5.Electric
connection
Circuit diagram of knock sensor
E-10
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