Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 1402

6E2–59

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

numbers 1 and 4 misfired, look for a circuit or component
common to both cylinders number 1 and 4.
Misfire counter information is located in the “Eng”. menu,
“Misfire Data” sub-menu of the data list.
The misfire diagnostic may indicate a fault due to a
temporary fault not necessarily caused by a vehicle
emission system malfunction. Examples include the
following items:

Contaminated fuel

Low fuel

Fuel-fouled spark plugs

Basic engine fault

Fuel Trim System Monitor Diagnostic

Operation

Fuel Trim System Monitor Diagnostic
Operation

This system monitors the averages of short-term and
long-term fuel trim values. If these fuel trim values stay at
their limits for a calibrated period of time, a malfunction is
indicated. The fuel trim diagnostic compares the
averages of short-term fuel trim values and long-term fuel
trim values to rich and lean thresholds. If either value is
within the thresholds, a pass is recorded. If both values
are outside their thresholds, a rich or lean DTC will be
recorded.
The fuel trim system diagnostic also conducts an intrusive
test. This test determines if a rich condition is being
caused by excessive fuel vapor from the EVAP canister.
In order to meet OBD II requirements, the control module
uses weighted fuel trim cells to determine the need to set
a fuel trim DTC. A fuel trim DTC can only be set if fuel trim
counts in the weighted fuel trim cells exceed
specifications. This means that the vehicle could have a
fuel trim problem which is causing a problem under
certain conditions (i.e., engine idle high due to a small
vacuum leak or rough idle due to a large vacuum leak)
while it operates fine at other times. No fuel trim DTC
would set (although an engine idle speed DTC or HO2S
DTC may set). Use the Tech 2 to observe fuel trim counts
while the problem is occurring.
A fuel trim DTC may be triggered by a number of vehicle
faults. Make use of all information available (other DTCs
stored, rich or lean condition, etc.) when diagnosing a fuel
trim fault.

Fuel Trim Cell Diagnostic Weights

No fuel trim DTC will set regardless of the fuel trim counts
in cell 0 unless the fuel trim counts in the weighted cells
are also outside specifications. This means that the
vehicle could have a fuel trim problem which is causing a
problem under certain conditions (i.e. engine idle high due
to a small vacuum leak or rough due to a large vacuum
leak) while it operates fine at other times. No fuel trim
DTC would set (although an engine idle speed DTC or
HO2S DTC may set). Use the Tech 2 to observe fuel trim
counts while the problem is occurring.

6E2–60

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

On-Board Diagnostic (OBD II) System Check

060R200048

Circuit Description

The on-board diagnostic system check is the starting
point for any driveability complaint diagnosis. Before
using this procedure, perform a careful visual/physical
check of the PCM and engine grounds for cleanliness and
tightness.
The on-board diagnostic system check is an organized
approach to identifying a problem created by an
electronic engine control system malfunction.

Diagnostic Aids

An intermittent may be caused by a poor connection,
rubbed–through wire insulation or a wire broken inside the
insulation. Check for poor connections or a damaged
harness. Inspect the PCM harness and connector for
improper mating, broken locks, improperly formed or
damaged terminals, poor terminal-to-wire connection,
and damaged harness.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
1.The MIL (“Check Engine lamp”) should be “ON”

steady with the ignition “ON ” and the engine “OFF”.
If not, the “No MIL” chart should be used to isolate
the malfunction.

2.The RPL (“Reduced Power lamp”) should be “ON”

steady with the ignition “ON ”and the engine “OFF”.
If not, the “No RPL”chart should be used to isolate
the malfunction.

3.Checks the Class 2 data circuit and ensures that the

PCM is able to transmit serial data.

4.This test ensures that the PCM is capable of

controlling the MIL (“Check Engine lamp”) and the
MIL (“Check Engine lamp”) driver circuit is not
shorted to ground.

5.This test ensures that the PCM is capable of

controlling the RPL (“Reduced Power lamp”) and
the RPL (“Reduced Power lamp”) driver circuit is not
shorted to ground.

7.Check the DTCs (System ,Volts Supply circuit).

8.Check the DTCs (PCM{Software} detect Errors).

11.If the engine will not start, the Cranks But Will Not

Run chart should be used to diagnose the condition.

14.A Tech 2 parameter which is not within the typical

range may help to isolate the area which is causing
the problem.

15.This vehicle is equipped with a PCM which utilizes

an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed. Refer to

PCM

Replacement and Programming Procedures in
Powertrain Control Module (PCM) and Sensors of
this section.

10. If the starter motor will not start, the starter control

system chart should be used to diagnose the
condition.

6E2–61

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

On-Board Diagnostic (OBD II) System Check

Step

Action

Value(s)

Yes

1. Ignition “ON”, engine “OFF”.
2. Observe the malfunction indicator lamp (MIL or

“Check Engine lamp”).

Is the MIL (“Check Engine lamp”)“ON”?

—

Go to

Step 2

Go to

MIL(“Check

Engine lamp”)

1. Ignition “ON”, engine “OFF”.
2. Observe the “Reduced Power lamp”.

Is the RPL (“Reduced Power lamp”) “ON”?

—

Go to

Step 3

Go to

RPL(“Reduce

d Power

lamp”)

1. Ignition “OFF”.
2. Install Tech 2.
3. Ignition “ON”.
4. Attempt to display PCM engine data with the

Tech 2.

Does the Tech 2 display PCM data?

—

Go to

Step 4

Go to

Step 12

1. Using the Tech 2 output tests function, select MIL

(“Check Engine lamp”) control and command the
MIL (“Check Engine Lamp”) “OFF”.

2. Observe the MIL (“Check Engine lamp”).

Did the MIL (“Check Engine lamp”) turn “OFF”?

—

Go to

Step 5

Go to

MIL(“Check

Engine lamp”)

On Steady

1. Using the Tech 2 output tests function, select MIL

(“Check Engine lamp”) control and command the
RPL (“Reduced Power lamp”) “OFF”.

2. Observe the RPL (“Reduced Power lamp”).

Did the MIL (“Reduced Power lamp”) turn “OFF”?

—

Go to

Step 6

Go to

RPL(“Reduce

d Power

lamp”) On

Steady

Select “Display DTCs” with the Tech 2.

Are any DTCs stored?

—

Go to

Step 7

Go to

Step 11

Stored DTCs.
P0562, P0563, P0601, P0602, P0604, P0606, P1625,
P1635, P1639, P1640, P1650

Are the applicable DTCs stored?

—

Go to

applicable
DTC table

Go to

Step 8

Stored DTCs.
P1514, P1515, P1516, P1523, P1125, P1290, P1295,
P1299

Are the applicable DTCs stored?

—

Go to

applicable
DTC table

Go to

Step 9

Stored DTCs.

1. P0425, P0106, P0107, P1107, P0401, P1404,

P0405, P1120, P1221, P1515, P1516, P1275,
P1635, P1271, P1273, P1285, P1272

2. P0336, P0337, P1220, P1515, P1221, P1516,

P1280, P1639, P1271, P1272

Are the applicable DTCs stored?

—

Go to

“Multiple

PCM

Information

sensor DTCs

Set”

Go to

Step 10

Attempt to crank the starter motor

Did the starter motor crank?

—

Go to

Step 10

Go to

Starter

control

system

Attempt to start the engine.

Did the engine start and continue to run?

—

Go to

Step 6

Go to

Cranks

But Will Not

Run

6E2–62

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

On-Board Diagnostic (OBD II) System Check

(Cont'd)

Step

Yes

Value(s)

Action

Compare PCM data values displayed on the Tech 2 to
the typical engine scan data values.

Are the displayed values normal or close to the typical
values?

—

Go to

Symptom

Refer to

indicated

Component

System
Checks

1.  Ignition “OFF”, disconnect the PCM.
2.  Ignition “ON”, engine “OFF”.
3.  Check the Class 2 data circuit for an open, short to

ground, or short to voltage. Also, check the DLC
ignition feed circuit for an open or short to ground
and the DLC ground circuit for an open.

4. If a problem is found, repair as necessary.

Was a problem found?

—

Go to

Step 2

Go to

Step 14

1. Attempt to reprogram the PCM. Refer to

Powertrain

Control Module (PCM) in On-Vehicle Service.

2. Attempt to display PCM data with the Tech 2.

Does the Tech 2 display PCM engine data?

—

Go to

Step 2

Go to

Step 15

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?

—

Go to

Step 2

—

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