Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Service manual - part 343

6E–402

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Rubbed through wire insulation.

Broken wire inside the insulation.

Check for the following conditions:

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.

Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe the
AP sensor 1, AP sensor 2, AP sensor 3 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 P1125 cannot be duplicated, the information
included in the Failure Records data can be useful in
determined vehicle mileage since the DTC was last
set.

If it is determined that the DTC occurs intermittently,
performing the DTC P1125 Diagnostic Chart may
isolate the cause of the fault.

DTC P1125 – ETC Limit Performance Model

Step

Action

Value(s)

Yes

Was the “On-Board (OBD) System Check” performed?

—

Go to

Step 2

Go to

OBD

System

Check

Was the “Electric Throttle Control (ETC) System
Check” performed?

—

Go to

Step 3

Go to

ETC

System

Check

Observe the AP angle reading on the Tech 2 while
slowly opening the throttle.

Does the AP angle increase steadily and evenly from
the closed throttle value to the wide open throttle
value?

Idle position

AP sensor 1

=13 % AP

sensor 2, 3

=85

∼

89 %

open throttle

AP sensor 1

=85

∼

89 %

AP sensor 2

=11

∼

15 %

Refer to

Diagnostic

Aids

Go to

Step 4

1. Disconnect the AP sensor.
2. Observe the AP sensor reading on the Tech 2.

Is the AP sensor reading near the specified value?

Go to

Step 5

Go to

Step 6

1. Connect a test light between the 5 Voltage supply

circuit and the AP1, AP2 AND AP3 sensor signal
circuit at the AP sensor harness connector.

2. Observe the AP sensor reading on the Tech 2.

Is the AP sensor reading near the specified value?

Go to

Step 7

Go to

Step 8

Check the following items;

1. AP1, AP2 or AP3 signal circuit for a short to voltage.
2. AP1, AP2 or AP3 sensor ground circuit for high

resistance between the PCM and the AP sensor.

3. AP1, AP2 or AP3 sensor ground circuit for a poor

connection.

4. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Verify repair

Go to

Step 9

6E–403

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P1125 – ETC Limit Performance Model

(Cont'd)

Step

Yes

Value(s)

Action

Check the following items;

1. AP1, AP2 or AP3 signal circuit or 5 voltage supply

circuit for a poor connection.

2. AP1, AP2 or AP3 signal circuit or 5 voltage supply

circuit for high resistance between the PCM and the
AP1, AP2 or AP3 sensor.

3. If a problem is found, repair wiring harness as

necessary.

Was a problem found?

—

Verify repair

Go to

Step 9

Replace the AP sensor.

Is the action complete?

—

Verify repair

—

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed. Refer to

ON-Vehicle Service in Power

Control Module and Sensors for procedures.

And also refer to latest Service Bulletin.

Check to see if the latest software is released or not.

And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.

Is the action complete?

—

Verify repair

—

6E–404

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC)

P1133 HO2S Insufficient Switching Bank 1 Sensor 1

060R200054

Circuit Description

The powertrain control module (PCM) monitors the
heated oxygen sensor (HO2S) activity for 90 seconds
after “closed loop” and stoichiometric operation have
been enabled. During this test period the PCM counts the
number of times that the HO2S signal voltage crosses the
rich-to-lean and lean-to-rich threshold. If the PCM
determines that the HO2S did not switch enough times,
DTC P1133 will be set.
A lean-to-rich switch is determined when the HO2S
voltage changes above and below 450 mV.
Heated oxygen sensors are used to minimize the amount
of time required for “closed loop” fuel control operation
and to allow accurate catalyst monitoring. The oxygen
sensor heater greatly decreases the amount of time
required for fuel control sensors Bank 1 HO2S 1 and Bank
2 HO2S 1 to become active. Oxygen sensor heaters are
required by post-catalyst monitor sensors to maintain a
sufficiently high temperature for accurate exhaust oxygen
content readings further from the engine.

Conditions for Setting the DTC

Engine coolant temperature (ECT) is above 60

(140

F).

Engine is operating in “closed loop”.

The engine has been running at least one minute.

Canister purge duty cycle is greater than 2%.

Engine speed is between 1500 RPM and 3000 RPM.

Mass air flow (MAF) is between 9 g/second and 42
g/second.

Above conditions are present for 3 seconds.

90 seconds after “closed loop” and stoichiometric
operation have been achieved, the PCM monitors the
oxygen sensor as it switches above and below 450 mV.
If fewer than 23 rich-to-lean and lean-to-rich switches
are detected, DTC P1133 will be set.

Action Taken When the DTC Sets

The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.

”Open loop” fuel control will be in effect.

The PCM will store conditions which were present
when the DTC was set as Freeze Frame and in the
Failure Records data.

Conditions for Clearing the MIL/DTC

The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

A history DTC P1133 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P1133 can be cleared by using Tech 2 “Clear Info”
function or by disconnecting the PCM battery feed.

6E–405

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Aids

A malfunction in the HO2S heater ignition feed or ground
circuit may cause a DTC P1133 to set. Check HO2S
heater circuitry for intermittent faults or poor connections.
If connections and wiring are OK and DTC P1133
continues to set, replace the Bank 1 HO2S 1.
Reviewing the Failure Records vehicle mileage since the
diagnostic test last failed may help to determine how often
the condition that caused the DTC to be set occurs. This
may assist in diagnosing the condition.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.

3. A condition that affects other heated oxygen sensors

indicates probable contamination. To avoid
damaging the replacement sensors, correct the
condition which caused the contamination before
replacing the affected sensors.

5. This step checks for conditions which may cause the

heated oxygen sensor to appear faulty. Correct any
of the described conditions if present.

11.To avoid damaging replacement sensors, correct the

condition which caused the contamination before
replacing the affected sensors.

DTC P1133 – HO2S Insufficient Switching Bank 1 Sensor 1

Step

Action

Value(s)

Yes

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to

Step 2

Go to

OBD

System

Check

IMPORTANT: If any DTCs are set (except P1153 or
P1154) refer to those DTCs before proceeding with this
diagnostic chart.

1. Engine idling at operating temperature.
2. Operating the vehicle within parameters specified

under “Conditions for Setting the DTC” criteria
included in Diagnostic Support.

3. Using a Tech 2, monitor “DTC” info for DTC P1133

until the DTC P1133 test runs.

4. Note the test result.

Does the Tech 2 indicate DTC P1133 failed this
ignition?

—

Go to

Step 3

Refer to

Diagnostic

Aids

Did the Tech 2 also indicate that the P1153 or P1154
tests failed?

—

Go to

Step 20

Go to

Step 4

Check for leaks at the exhaust pipe joints.

Are the joints leaking?

—

Go to

Step 5

Go to

Step 6

Tighten the bolt/nuts at the leaking joints.

Is your action complete?

—

Go to

Step 2

—

Check for gaskets that are damaged or improperly
installed.

Are there damaged or misaligned gaskets?

—

Go to

Step 7

Go to

Step 8

1. Replace the damaged gaskets.
2. Align the connections.
3. Tighten the connections.

Is your action complete?

—

Go to

Step 2

—

Check for loose exhaust flange connections.

Are the flange connections loose?

—

Go to

Step 9

Go to

Step 10

Tighten the stud nuts or bolts to specifications.

Is your action complete?

—

Go to

Step 2

—

Check for burned or corroded exhaust pipes.

Are the exhaust pipes burned or corroded?

—

Go to

Step 11

Go to

Step 12

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