FAILURE DIAGNOSIS
1-158
TNV DI Service Manual
Method and Procedure of Failure Diagnosis
Work Description
1. Check of the sensor resistance value (sensor only):
• Remove the harness from the cooling water temperature sensor.
• Measure the resistance between cooling water temperature sensor terminals A and B using a circuit
tester.
• Check if the measured resistance value is within the normal range, referring to the following table
<Characteristics of cooling water temperature sensor>.
<Characteristics of cooling water temperature sensor>
• Relationship between cooling water temperature and sensor resistance
2. Check of the sensor resistance value ( harness):
• Connect the cooling water temperature sensor and the harness, and remove E-ECU from the harness.
• Measure the resistance between harness side E-ECU connector terminals E16 (E25) and E28 using a
circuit tester.
• Check if the measured resistance value is within the normal range, referring to the above table
<Characteristics of cooling water temperature sensor>.
-40
0
40
80
120
0.1
1
10
100
-40
0
40
80
120
017541-00E
Temperature (°C)
Temperature (°C)
Resistance [kΩ]
Temperature
(°C)
Resistance [k
Ω
]
High-precision Conventional
-30
25.4
28.6
-20
15.04
16.2
-10
9.16
9.56
0
5.74
5.88
10
3.7
3.73
20
2.45
2.45
30
1.66
1.65
40
1.15
1.14
50
0.811
0.808
60
0.584
0.584
70
0.428
0.43
80
0.318
0.322
90
0.24
0.245
100
0.1836
0.189
110
0.1417
0.148
120
0.1108
0.117
High-accuracy cooling water
temperature sensor
Conventional cooling water
temperature sensor
NG
Replace the cooling water temperature sensor.
OK
Check the sensor resistance with the sensor and the harness being connected.
→
Go to [2. Check of the sensor resistance value ( harness):]
NG
Check the harness for correct continuity.
→
Go to [3. Check of harness continuity:]
OK
Check the output voltage of the cooling water temperature sensor.
→
Go to [4.
Output voltage check of the cooling water temperature sensor:]
TNV_DI_SM_A4-Troubleshooting.book 158 ページ 2007年11月15日 木曜日 午後5時27分