Isuzu Trooper (1998-2002 year). Manual - part 482

6E–298

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC)

P0445 EVAP Purge Control Circuit Short

D06R200089

Circuit Description

The canister purge solenoid valve is controlled by the
Power Train Control Module (PCM). The PCM monitors
vacuum level via the fuel tank pressure sensor input.
At an appropriate time, the EVAP canister purge solenoid
is “ON,” allowing engine vacuum to draw a small vacuum
on the entire evaporative emissions system.

Conditions for setting the DTC

The Ignition is “ON”.

Engine is running.

System voltage is between 11.5 volts and 16 volts.

Action Taken When the DTC Sets

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

The PCM will store conditions which were present
when the DTC 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 P0445 will clear after 40 consecutive trip
cycles during which the warm up cycles have occurred
without a fault.

DTC P0445 can be cleared using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

An intermittent may be caused by the following:

Poor connections.

Misrouted harness.

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
EVAP purge solenoid 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 P0445 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 P0445 Diagnostic Chart may
isolate the cause of the fault.

6E–299

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0445 EVAP Purge Control Circuit Short

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

1. Install the Tech 2.
2. Ignition is “ON”,
3. Observe the EVAP purge solenoid reading on the

Tech 2.

Is the EVAP purge solenoid reading near the specified
value?

Check the

Procedure

Refer to

Diagnostic

Aids

Go to

Step 3

Check the signal circuit for canister purge solenoid
valve.

1. Ignition is “OFF”.
2. Disconnect the canister purge solenoid valve.
3. Disconnect the PCM.
4. Check the circuit between EVAP purge solenoid

connector and PCM connector.

Is the problem found?

—

Go to

Step 4

Go to

Step 5

Repair the circuit as necessary. Is the action complete?

—

Verify repair

—

Check the canister purge solenoid valve.
Using a DVM, measure resistance for purge solenoid
valve connector terminal.

Is the purge solenoid valve resistance within the
specified values?

25–30 (at

F{20

C})

Go to

Step 7

Go to

Step 6

Replace the canister purge solenoid valve.

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–300

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P0502 VSS Circuit Low Input

D06R200016

Circuit Description

The vehicle speed sensor has a magnet rotated by the
transmission output shaft. Attached to the sensor is a hall
effect circuit the interacts with the magnetic field treated
by the rotating magnet. A 12-volt operating supply for the
speed sensor hall circuit is supplied from the meter fuse.
The VSS pulses to ground the 9-volt signal sent from the
powertrain control module (PCM) on the reference circuit.
The PCM interprets vehicle speed by the number of
pulses to ground per second on the reference circuit.

Conditions for Setting the DTC

Engine is running.

Engine speed is between 1800 RPM and 2500 RPM.

Throttle angle is between 10% and 40%.

Engine load is greater than 50 kPa.

PCM detects no VSS signal for 12.5 seconds over a
period of 15 seconds.

Action Taken When the DTC Sets

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

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 P0502 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

DTC P0502 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart.
10. To avoid backprobing the VSS and possibly

damaging a seal or terminal, the VSS output can be
tested at the point where the transmission harness
connects to the engine harness. Power and ground
are applied by jumpers to the VSS through the
connectors which are located to the rear of the air
cleaner assembly. The VSS signal is monitored
with a DVM as the rear driveshaft turns. The
wheels can be turned to rotate the driveshaft, or in
2-wheels-drive vehicles the driveshaft can be turned
directly.

6E–301

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

DTC P0502 – VSS Circuit Low Input

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

Does the speedometer work?

—

Go to

Step 10

Go to

Step 3

1. Disconnect the VSS connector.
2. Ignition “ON”.
3. Using a test light to battery +, probe the connector

ground wire.

Did the light illuminate?

—

Go to

Step 5

Go to

Step 4

Repair the sensor ground.

Is the action complete?

—

Verify repair

—

1. Ignition “ON”, sensor disconnected.
2. Using a DVM, measure at the VSS connector

between ground and voltage supply.

Was the measurement near the specified value?

Battery

voltage

Go to

Step 7

Go to

Step 6

Repair the open or short to ground which may have
blown the meter fuse.

Is the action complete?

—

Verify repair

—

1. Ignition “ON”, VSS disconnected.
2. Using a DVM, measure at the VSS connector

between ground and the wire from the
speedometer.

Was the measurement near the specified value?

7.5-8 V

Go to

Step 9

Go to

Step 8

Check for an open or short circuit between the
speedometer and the VSS.

Was an open or short circuit located?

—

Verify repair

Go to

Step 9

Replace the speedometer.

Is the action complete?

—

Verify repair

—

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