Isuzu 2000 Trooper Workshop Manual page 1049

6E–180
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
damaged terminals, poor terminal-to-wire connection,
and damaged harness.
D Faulty HO2S heater or heater circuit – With the ignition
"ON," engine "OFF," after a cool down period, the
HO2S 1 voltage displayed on the Tech 2 is normally
455-460 mV. A reading over 1000 mV indicates a
signal line shorted to voltage. A reading under 5 mV
indicates a signal line shorted to ground or signal lines
shorted together. Disconnect the HO2S and connect
a test light between the HO2S ignition feed and heater
ground circuits. If the test light does not light for 2
seconds when the ignition is turned on, 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.
D Intermittent test – With the Ignition "ON," monitor the
HO2S signal voltage while moving the wiring harness
DTC P0134 –HO2S Circuit Insufficient Activity Bank 1 Sensor 1
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 1 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 P0134
until the DTC P0134 test runs.
4. Note the test result.
Does the Tech 2 indicate DTC P0134 failed this
ignition?
4 Check for a damaged harness.
Was a problem found?
5 Check for poor Bank 1 HO2S 1 high and low circuit
terminal connections at the Bank 1 HO2S 1 harness
connector and replace terminal(s) if necessary.
Did any terminals require replacement?
6 Check for poor Bank 1 HO2S 1 high and low circuit
terminal connections at the PCM and replace terminals
if necessary.
Did any terminals require replacement?
7 1. Ignition "OFF."
2. With the PCM disconnected, check continuity of the
Bank 1 HO2S 1 high circuit.
3. If the Bank 1 HO2S 1 high circuit measures over 5.0
ohms, repair open or poor connection as necessary.
Was a Bank 1 HO2S 1 high circuit problem found and
corrected?
Action
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 P0134 test passes while the Failure
Records conditions are being duplicated, an
intermittent conditions 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
—
Go to Step 3
400-500 mV
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