Isuzu C22NE Workshop Manual page 328

6E1-158 DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:
• Poor connection at ECM - Inspect harness
connectors for backed-out terminals, improper
mating, broken locks,
damaged terminals, and poor terminal-to-wire
connection.
• Damaged harness - Inspect the wiring harness for
damage, If the harness appears to be OK, observe
the ECT display on the Scan Tool while moving
connectors and wiring harnesses related to the ECT
sensor. A change in the ECT display will indicate
the location of the fault.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Verifies that the fault is present.
3. Refer to the "Temperature vs. Resistance Value"
table. The table may be used to test the ECT
sensor at various temperatures to evaluate the
possibility of a "shifted" sensor that may be stored
Engine Coolant Temperature (ECT) Sensor Circuit Low Input
Step
Was the "On-Board Diagnostic (OBD) System Check"
1 performed?
2 1. Ignition ON, engine OFF
2. Observe the "Eng Coolant Temp" displayed on the
Scan Tool.
Is the "Eng Coolant Temp" below the specified value?
1. Ignition ON, engine OFF.
2. Using a Scan Tool, monitor info for Diagnostic Trouble
3
Code 15.
Does the Scan Tool indicate Diagnostic Trouble Code 15?
1. Disconnect the ECT sensor electrical connector.
2. Observe the "Eng Coolant Temp" displayed on the
4
Scan Tool.
Is the "Eng Coolant Temp" at the specified value?
improperly formed or
DTC (Flash DTC = 15)
Action
above or below a certain temperature. If this is the
case, replace the ECT sensor. If the ECT sensor
appears to be OK, the fault is intermittent; refer to
Diagnostic Aids.
Engine Coolant Temperature Sensor
°C
Temperature vs. Resistance Values
(approximate)
100
80
60
45
35
25
15
5
−5
−15
−30
−40
Value(s)
-
140°C
(284°F)
-
−35°C
(−31°F)
°F OHMS
212 177
176 332
140 667
113 1188
95 1802
77 2796
59 4450
41 7280
23 12300
5 21450
−22
52700
−40
100700
Yes No
Go to OBD
System
Go to Step 2 Check
Go to Step 4 Go to Step 3
Refer to
Diagnostic
Go to Step 4 Aids
Go to Step 6 Go to Step 5