Isuzu Trooper (1998-2002 year). Manual - part 476

6E–274

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0356 Ignition 6 Control Circuit

D06R200098

Circuit Description

ION Sensing Module has the function to energize and
de-energize the primary ignition coil in response to
signals from the PCM. The PCM controls ignition timing
and dwell time.
This diagnosis detects open circuit or short-circuiting in
the Ignition Electronic Spark Timing (EST) line by
monitoring EST signals. A failure determination is made
when the signal voltage remains higher or lower than the
threshold for corresponding fault code beyond a
predetermined time period.
When the PCM detects a problem on EST control circuit
6, it will set a DTC P0356.

Conditions for Setting the DTC

D

The ignition is “ON”.

D

The engine is running, determined by the 58X
crankshaft position input signal.

D

The output voltage is not equal to 5 volts when output
is “ON”.

D

The output voltage is not equal to 0 volts when output
is “OFF”.

D

Ten test failures occur within 10 samples of continuous
circuit monitoring.

Action Taken When the DTC Sets

D

The PCM will illuminate the malfunction indicator lamp
(MIL) the first time the fault is detected.

D

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

D

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

D

A history DTC P0356 will clear after 40 consecutive
warm-up cycles occur without a fault.

D

DTC P0356 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

6E–275

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Aids

Check for the following conditions:

D

Poor connection at PCM – Inspect the harness
connectors for backed-out terminals, improper mating,
broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connections.

D

Damaged harness – Inspect the wiring harness for
damage.  If the harness appears to be OK, observe the

Tech 2 display related to DTC P0356 while moving the
connector and wiring related to the ignition system.  A
change in the display will indicate the location of the
fault.

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.

DTC P0356 – Ignition 6 Control Circuit

 

Step

Action

Value(s)

Yes

No

1

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

—

Go to 

Step 2

Go to 

OBD

System

Check

2

1. Ignition “ON”, engine “OFF”.
2. Review and record Tech 2 Failure Records data.
3. Operate the vehicle within Failure Record

conditions as noted.

4. Use a Tech 2 to monitor the “DTC” information for

DTC P0356 until the DTC P0356 test runs.

5. Note the test result.

Does the Tech 2 indicate DTC P0356 failed this ignition
cycle?

—

Go to 

Step 3

Check the

Procedure

Refer to

Diagnostic

Aids

3

Check for faulty connection at ignition coil.

Was a problem found?

—

Verify repair

Go to 

Step 4

4

Check for faulty connection at PCM connector.

Was a problem found?

—

Verify repair

Go to 

Step 5

5

1. Ignition “ON”, engine “OFF”.
2. Back probe the ignition control circuit 6 at the ION

Sensing Module with a DVM positive lead with the
negative lead to ground.

Is the voltage near the specified value?

25-55 mV

Go to 

Step 6

Go to 

Step 9

6

1. Ignition “ON”, engine running.
2. Back probe the ignition control circuit at the ION

Sensing Module for the cylinder being tested.

Is the voltage in the specified range, rapidly toggling
back and forth to a reading 20-50 mV higher?

100-180 mV

Go to 

Step 7

Go to 

Step 13

7

1. Ignition “OFF”.
2. Disconnect the 3-pin connector at the ignition coil.
3. Check ignition control circuit 6 voltage at the ignition

coil connector while cranking the engine.

Does the voltage measure between the specified
values?

200-1200 mV

Go to 

Step 8

Go to 

Step 11

8

Replace the ignition coil.

Is the action complete?

—

Verify repair

—

9

1. Ignition “OFF”.
2. Disconnect the PCM and the ignition coil.
3. Check ignition control circuit 6 for short to ground.

Was a problem found?

—

Verify repair

Go to 

Step 10

10

Check ignition control circuit 6 for short to voltage.

Was a problem found?

—

Verify repair

Go to 

Step 13

6E–276

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

DTC P0356 – Ignition 6 Control Circuit

  (Cont'd)

Step

No

Yes

Value(s)

Action

11

Check for an open ignition control circuit 6.

Was the ignition control circuit open?

—

Go to 

Step 12

Go to 

Step 13

12

Repair the open ignition control circuit.

Is the action complete?

—

Verify repair

—

13

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.  Refer to 

On-Vehicle Service in

Powertrain 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–277

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0401 EGR Flow Insufficient

D06R200075

Circuit Description

The powertrain control module (PCM) tests the exhaust
gas recirculation (EGR) system during deceleration by
momentarily commanding the EGR valve to open while
monitoring the manifold absolute pressure (MAP) sensor
signal.  When the EGR valve is opened, the PCM
monitors the change in MAP input signal.  The PCM
compares the MAP change to a RPM vs. BARO table.
When the PCM interprets the change in MAP to be out of
limits, the PCM will set DTC P0401.  The number of test
samples required to accomplish this may vary according
to the severity of the detected flow error.
Normally, the PCM will only allow one EGR flow test
sample to be taken during an ignition cycle.  To aid in
verifying a repair, the PCM allows twelve test samples
during the first ignition cycle following a Tech 2 “Clear Info”
or a battery disconnect.  Between nine and twelve
samples should be sufficient for the PCM to determine
adequate EGR flow and pass the EGR test.

Conditions for Setting the DTC

D

No TP sensor, vehicle speed sensor (VSS), MAP
sensor, IAT sensor, IAC, EGR Pintle Position sensor,
ECT sensor, misfire, or automatic transmission DTCs
set.

D

Engine coolant temperature is greater than 60

°

C

(140

°

F).

D

Ignition voltage between 11.5 and 16 volts.

D

Vehicle speed is greater than 24 km/h (15 mph).

D

A/C clutch status is unchanged.

D

TCC status is unchanged.

Start Test

D

TP angle is less than 0.8%.

D

EGR duty cycle is less than 1%.

D

MAP is steady, changing less than 2 kPa.

D

Engine speed is between 1100 RPM and 2000 RPM
(M/T).

D

MAP between 10 kPa and 40 kPa.

D

Engine speed is between 900 RPM and 1500 rpm
(A/T).
The test will be aborted if the vehicle speed changes
by more than 16 km/h (10 mph), engine speed
changes by more than 100 RPM or the EGR is
opened less than 95% of commanded position.

D

The PCM will only run the EGR test during a closed
throttle condition.

D

The PCM will only run the EGR test at vehicle speeds
above 24 km/h (15 mph).

D

Several deceleration cycles will be necessary to run a
sufficient number of EGR flow tests.

Action Taken When the DTC Sets

D

The PCM will ON the MIL after second trip with
detected fault.