Isuzu 2000 Trooper Workshop Manual page 1033

6E–164
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
DTC P0125 set indicates a faulty ECT sensor.
Comparing the engine coolant temperature displayed on
a Tech 2 with actual coolant temperature measured with a
thermometer may isolate this condition. If the displayed
engine coolant temperature is not close to the actual
coolant temperature, replace the ECT sensor.
Check for the following conditions:
D Poor connection at PCM – Inspect harness connectors
for backed-out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal-to-wire connection.
D Damaged harness – Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
display on the Tech 2 while moving connectors and
wiring harnesses related to the sensor. A change in the
display will indicate the location of the fault.
If DTC P0125 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage wince the DTC was last set.
Test Description
Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. Comparing the engine coolant temperature displayed
on a Tech 2 with actual coolant temperature
measured with a thermometer may isolate this
condition. If the displayed engine coolant
temperature is not close to the actual coolant
temperature, replace the ECT sensor. If the
temperatures are close, the fault is intermittent;
refer to Diagnostic Aids .
DTC P0125 –ECT Excessive Time to Closed Loop Fuel Control
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 Are any ECT sensor DTCs set?
3 1. Allow the engine to cool completely.
2. Check the cooling system coolant level (refer to
Cooling and Radiator ).
Is the coolant level OK?
4 1. Start the engine.
2. With the engine idling, monitor "ENG COOL TEMP"
display on the Tech 2.
Does "ENG COOL TEMP" increase to above the
specified value within 2 minutes?
5 Check for proper operation of the thermostat (refer to
Cooling and Radiator ).
Is the thermostat operating correctly?
Action
Engine Coolant Temperature
°C
Temperature vs. Resistance Values
(approximate)
100
80
60
45
35
25
15
5
–5
–15
–30
–40
Value(s)
— Go to Step 2
applicable
ECT sensor
—
DTC chart
— Go to Step 4
Diagnostic
21°C (70°F)
— Go to Step 6
°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
Check
Go to
Go to Step 3
Go to Step 9
Refer to
Aids Go to Step 5
Go to Step 9