Toyota 1KZ-TE Repair Manual page 142

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DI- -78
DT C
CIRCUIT DESCRIPTION
Fig. 1
30
20
10
5
3
2
1
0.5
0.3
0.2
0.1
- -20
0
(- -4) (32) (68) (104) (140) (176) (212)
Temperature ˚C (˚F)
DTC No.
Open or short in fuel temperature sensor circuit for 0.5 se-
39
conds or more
HI NT:
After confirming DTC 39, use the hand--held tester to confirm the water temperature from the CURRENT
DATA.
Displayed Temperature
140˚C (284˚F) or more
1KZ- -TE ENGINE SUP (RM790E)
DIAGNOSTICS
39 Fuel Tem p. Sensor Ci rcuit M alfuncti on
Acceptable
100
20 40 60 80
FI4741
DTC Detection Condition
- -40˚C (- -40˚F)
- - ENGINE
The fuel temperature sensor senses the fuel temperature. A
thermistor built in the sensor changes the resistance value ac-
cording to the fuel temperature. The lower the fuel temperature
is, the greater the thermistor resistance value becames, and the
higher the fuel temperature,is the lower the thermistor resis-
tance value (See Fig. 1) becames.
The fuel temperature sensor is connected to the engine ECU
(See below). The 5 V power source voltage in the engine ECU
is applied to the fuel temperature sensor from terminal THF via
a resistor R. That is, resistor R and the fuel temperature sensor
are connected in series. When the resistance value of the fuel
temperature sensor changes in accordance with changes in the
fuel temperature, the potential at terminal THF also changes.
Based on this signal, the engine ECU increases the fuel injec-
tion volume to improve driveability during low engine revolution
and high fuel temperature.
S Open or short in fuel temp. sensor circuit
S Fuel temp. sensor
S Engine ECU
1KZ-TE PAGES FROM SUPPLEMENT
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Trouble Area
Malfunction
Open circuit
Short circuit
DI8FM- -01
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