Isuzu Trooper (2000 year). Manual - part 301

6E–333

TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

D

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.

D

Damaged harness–Inspect the wiring harness to the
EVAP canister vent solenoid, EVAP canister purge
solenoid and the fuel tank pressure sensor for an
intermittent open or short circuit.

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.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. If an EVAP canister vent solenoid or an EVAP

canister purge solenoid electrical fault is present,
the purge system will not operate correctly.
Repairing the electrical fault will very likely correct
the condition that set DTC P0442.

3. Checks the fuel tank pressure sensor at ambient

pressure.

4. Verifies that the fuel tank pressure sensor accurately

reacts to EVAP system pressure changes.

DTC P0442 – EVAP System Leak Detected

 

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 “OFF.”
2. Remove the fuel cap.
3. Ignition “ON.”
4. Observe “Fuel Tank Pressure” on the Tech 2.

Does the Tech 2 indicate “Fuel Tank Pressure” at the
specified value?

1.51V

Go to 

Step 3

Go to 

Fuel

Tank

Pressure

System

3

IMPORTANT: Before continuing with diagnosis, zero
the EVAP pressure and vacuum gauges on EVAP
pressure/purge cart J 41413 (refer to tool operating
instructions).

1. Replace the fuel cap.
2. Capture Failure Records data for DTC P0442 and

clear DTCs.

3. Connect the EVAP pressure/purge cart J 41413 to

the EVAP service port.

4. Using the Tech 2, command the EVAP canister vent

solenoid “ON” (closed).

5. Using the EVAP pressure/purge cart J 41413,

pressurize the EVAP system to the specified value.

6. Observe “Fuel Tank Pressure” on the Tech 2.

Does the Tech 2 indicate “Fuel Tank Pressure” at the
specified value?

1.47V

Go to 

Step 4

Go to 

Fuel

Tank

Pressure

System

4

1. Ignition “ON,” engine idling.
2. Using the Tech 2, command the EVAP canister vent

solenoid “ON” (closed).

3. Using the EVAP pressure/purge cart J 41413,

pressurize the EVAP system to 15 in. H2O.

4. Switch the rotary switch on the cart to “HOLD” and

observe the EVAP pressure gauge.

Does the pressure decrease to less than the specified
value within 2 minutes?

1.47 – 1.51V

Go to 

Step 5

Refer to

Diagnostic

Aids

6E–334

TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0442 – EVAP System Leak Detected

  (Cont'd)

Step

No

Yes

Value(s)

Action

5

1. Disconnect the fuel tank vapor line and the EVAP

purge line from the EVAP canister.

2. Block the canister fitting for the fuel tank vapor line.
3. Connect a hand vacuum pump to the canister fitting

for the EVAP purge line.

4. Ensure that the EVAP canister vent solenoid is still

commanded “ON” (closed).

5. Attempt to apply vacuum to the EVAP canister.

Can the vacuum be maintained at the specific value?

1.46V

Go to 

Step 8

Go to 

Step 6

6

1. Visually/physically check for the following

conditions:

D

Vent hose disconnected or damaged.

D

EVAP canister damaged.

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

Was a problem found?

—

Go to 

Step 10

Go to 

Step 7

7

Replace the EVAP canister vent solenoid.

Is the action complete?

—

Go to 

Step 10

—

8

1. Visually/physically check for the following

conditions:

D

Missing or faulty fuel cap.

D

Disconnected or leaking fuel tank vapor line.

D

Disconnected or damaged EVAP purge line.

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

Was a problem found?

—

Go to 

Step 10

Go to 

Step 9

9

1. Using Tech 2, command the EVAP canister vent

solenoid “ON” (closed).

2. With the cart connected to the EVAP service port,

continuously attempt to pressurize the EVAP
system by leaving the cart control knob in the
pressurize position.

3. Using ultrasonic leak detector J 41416, locate and

repair leak in EVAP system. (It may be necessary to
partially lower the fuel tank to examine the
connections on top of the tank.)

Is the action complete?

—

Go to 

Step 10

—

10

1. Ignition “ON,” engine not running.
2. Using the Tech 2, command the EVAP canister vent

solenoid “ON” (closed).

3. Using the EVAP pressure/purge cart J 41413,

pressurize and monitor the EVAP system to 15 in.
H2O.

4. Switch the rotary switch on the cart to “HOLD” and

observe the EVAP pressure gauge.

Does the pressure decrease to less than the specified
value within 2 minutes?

2.14V

Go to 

Step 2

Verify repair

6E–335

TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0446 EVAP Canister Vent Blocked

D06RY00128

Circuit Description

The evaporative system includes the following
components:

D

Fuel tank

D

EVAP canister vent solenoid

D

Fuel tank pressure sensor

D

Fuel pipes and hoses

D

Vapor lines

D

Fuel cap

D

Evaporative emissions canister

D

Purge lines

D

EVAP canister purge solenoid

An incorrect fuel tank pressure sensor signal is detected
by monitoring fuel tank pressure when the key is first
turned “ON” during a cold start.  If the fuel tank pressure
signal is out of range, DTC P0446 will set. A restricted or
blocked EVAP vent path is detected by monitoring fuel
tank pressure during normal operation (EVAP canister
vent solenoid open, EVAP canister purge solenoid
normal).  With the EVAP canister vent solenoid open,
vacuum level in the system should be very low unless the
vent path is blocked.  A blockage can be caused by the
following condition:

D

Faulty EVAP canister vent solenoid (stuck closed).

D

Plugged, kinked or pinched vent hose.

D

Shorted EVAP canister vent solenoid driver circuit.

D

Plugged evaporative canister.

If any of these conditions are present, DTC P0446 will set.

Conditions for Setting the DTC

D

No TP sensor, ECT sensor, Tank pressure sensor, IAT
sensor, or MAP sensor DTCs set.

D

Start-up engine coolant temperature is less than 32

°

C

(90

°

F).

D

Start-up engine coolant temperature is not more than
7

°

C (13

°

F) greater than start-up intake air

temperature.

D

Vehicle speed is less than 75 mph (120 km/h).

D

Throttle position is greater than 7% but less than 30%.

D

Minimal fuel slosh.

D

Fuel tank level is between 10% and 90%.

D

BARO is greater than 70 kPa.

Action Taken When the DTC Sets

D

The PCM will illuminate the MIL during the second key
cycle in which the DTC sets.

D

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

Conditions for Clearing the MIL/DTC

D

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.

D

A history DTC P0446 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

6E–336

TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

D

DTC P0446 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

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.

D

Damaged harness–Inspect the wiring harness to the
EVAP canister vent solenoid, EVAP canister purge
solenoid and the fuel tank pressure sensor for an
intermittent open or short circuit.

D

Kinked, pinched, or plugged vent hose–Verify that the
vent hose between the EVAP canister and EVAP
canister vent solenoid is not restricted.

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.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
2. If a vent solenoid electrical fault is present, the purge

system will not operate correctly.  Repairing the
electrical fault will very likely correct the condition
that set DTC P0446.

3. Checks the fuel tank pressure sensor at ambient

pressure.

4. Verifies that the fuel tank pressure sensor accurately

reacts to EVAP system pressure changes.

6. Checks for a blocked EVAP canister.

DTC P0446– EVAP Canister Vent Blocked

 

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.”
2. Capture Failure Records data for DTC P0446 and

clear DTCs.

3. Ignition “OFF.”
4. Remove the fuel cap.
5. Ignition “ON.”
6. Observe “Fuel Tank Pressure” on the Tech 2.

Does Tech 2 indicate “Fuel Tank Pressure” at the
specified value?

1.51V

Go to 

Step 3

Go to 

Fuel

Tank

Pressure

System

3

IMPORTANT: Before continuing with diagnosis, zero
the EVAP pressure and vacuum gauges on the EVAP
pressure/purge cart J 41413 (refer to tool operating
instructions).

1. Replace the fuel cap.
2. Using the Tech 2, command the EVAP vent solenoid

“ON” (closed).

3. Connect the EVAP pressure/purge cart J 41413 to

the EVAP service port.

4. Using the EVAP pressure/purge cart J 41413,

pressurize the EVAP system to the specified value.

5. Observe “Fuel Tank Pressure” on the Tech 2.

Does Tech 2 indicate “Fuel Tank Pressure” at the
specified value?

1.52 – 1.69V

Go to 

Step 4

Go to 

Fuel

Tank

Pressure

System

4

1. Maintain the EVAP pressure at 5 in. at H2O.
2. Using Tech 2, command the EVAP vent solenoid

“OFF” (open) while observing the EVAP pressure
gauge on the cart J 41413.

Does the EVAP pressure return to the specified value
within 5 seconds?

0 in. H2O

Refer to

Diagnostic

Aids

Go to 

Step 5