Isuzu 2000 Trooper Workshop Manual page 1061

6E–192
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Aids
Check for the following conditions:
D Poor connection or damaged harness– Inspect the
harness connectors
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
D Faulty HO2S heater or heater circuit–With the
ignition"ON," engine "OFF," the HO2S voltage
displayed on a Tech 2 should gradually drop to below
250 mV. If not, disconnect the HO2S and connect a
test light between the HO2S ignition feed and heater
ground circuits. If the test light does not light, repair the
open ignition feed or sensor ground circuit as
necessary. If the test light lights and the HO2S signal
and low circuits are OK, replace the HO2S.
DTC P0140 – HO2S Circuit Insufficient Activity BANK 1 SENSOR 2
Step
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
2 1. Install the Tech 2.
2. Run the engine at operating temperature.
3. Operate the engine above 1200 RPM for two
minutes.
Does the Tech 2 indicate Bank 1 HO2S 2 voltage
varying outside the specified values?
3 1. Ignition "ON," engine "OFF," review and record Tech
2 Failure Records data and note parameters.
2. Operate the vehicle within Failure Records
conditions as noted.
3. Using a Tech 2, monitor "DTC" info for DTC P0140
until the DTC P0140 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0140 failed this
ignition?
4 Check for a damaged harness.
Was a problem found?
5 Check for poor Bank 1 HO2S 2 high and low circuit
terminal connections at the Bank 1 HO2S 2 harness
connector and replace terminal(s) if necessary.
Did any terminals require replacement?
6 Check for poor Bank 1 HO2S 2 high and low circuit
terminal connections at the PCM
terminal(s) if necessary.
Did any terminals require replacement?
7 1. Ignition "OFF."
2. With the PCM disconnected, check continuity of the
Bank 1 HO2S 2 high circuit.
3. If the Bank 1 HO2S 2 high circuit measures over 5.0
ohms, repair open or poor connection as necessary.
Was a Bank 1 HO2S 2 high circuit problem found and
corrected?
for backed-out terminals,
Action
and replace
D Intermittent test–With the ignition "ON," monitor the
HO2S signal voltage while moving the wiring harness
and related connectors. If the fault is induced, the
HO2S signal voltage will change. This may help isolate
the location of the malfunction.
Test Description
Number (s) below refer to the step number (s) on the
Diagnostic Chart.
3. If the DTC P0140 test passes while the Failure
Records conditions are being duplicated, an
intermittent condition is indicated.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.
Value(s)
— Go to Step 2
425-475 mV Go to Step 3
— Go to Step 4
— Verify repair
— Verify repair
— Verify repair
— Verify repair
Yes No
Go to OBD
System
Check
Go to Step 4
Refer to
Diagnostic
Aids
Go to Step 5
Go to Step 6
Go to Step 7
Go to Step 8