TGE/Troubleshooting 2JZ-GE — Dtc 22 Engine Coolant Temp. Sensor Circuit, page 44

EG–424

ENGINE – 2JZ–GE ENGINE TROUBLESHOOTING

DTC 22 Engine Coolant Temp. Sensor Circuit

CIRCUIT DESCRIPTION

The engine coolant temperature sensor senses the coolant temperature. A thermistor built in the sensor changes its resistance value according to the coolant temperature. The lower the coolant temperature, the greater the thermistor resistance value, and the higher the coolant temperature, the lower thermistor resistance value (See Fig. 1.).
The engine coolant temperature sensor is connected to the ECM (See wiring diagram). The 5 V power source voltage in the ECM is applied to the engine coolant temperature sensor from the terminal THW via a resistor R. That is, the resistor R an the engine coolant temperature sensor are connected in series. When the resistance value of the engine coolant temperature sensor changes in accordance with the changes in the coolant temperature the potential at the terminal THW also changes. Based on this signal, the ECM increases the fuel injection volume to improve driveability during cold engine operation. If the ECM detects the diagnostic trouble code 22, it operates the fail safe function in which the engine coolant temperature is assumed to be 80°C (176°F).

(fig-1)

Resistance kΩ
30
20
10
5
3
2
1
0.5
0.3
0.2
0.1

Acceptable

–20  0  20  40  60  80  100
(–4) (32)(68)(104)(140)(176)(212)
Temperature °C (°F)

FI4741

Reference

Engine Coolant Temp.
°C (°F) | Resistance (kΩ) | Voltage (V)

–20 (–4) | 16.2 | 4.3
0 (32) | 5.9 | 3.4
20 (68) | 2.5 | 2.4
40 (104) | 1.1 | 1.4
60 (140) | 0.6 | 0.9
80 (176) | 0.3 | 0.5
100 (212) | 0.2 | 0.3

DTC No. | Diagnostic Trouble Code Detecting Condition | Trouble Area

22 | Open or short in engine coolant temp. sensor circuit for 0.5 sec. or more | • Open or short in engine coolant temp. sensor circuit
• Engine coolant temp. sensor
• ECM

WIRING DIAGRAM

Engine Coolant Temp. Sensor

2    L-Y

1    BR-B

Engine Control Module

44
THW  R
⊕5V

65  E2
E1

FI8448