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Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 259

6E–66

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

Use an ohmmeter to check continuity between the
pressure switch and the A/C thermostat relay.

Was the circuit open?

—

Go to

Step 22

Go to

Step 23

Repair the open circuit between the pressure switch
and the A/C thermostat relay.

Is the action complete?

—

Verify repair

—

Check for damaged pin or terminal at F45 of the PCM.

Was a damaged pin or terminal found?

—

Go to

Step 24

Go to

Step 25

Repair the damaged pin or terminal.

Is the action complete?

—

Verify repair

—

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed. Refer to

On-Vehicle Service in

Powertrain Control Module 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

—

1. Remove the A/C compressor relay.
2. Ignition “ON”.
3. Use a DVM to check voltage at both of the wires at

the A/C compressor relay socket.

Is the voltage equal to the specified value?

B+

Go to

Step 28

Go to

Step 27

Repair the faulty wire between the A/C fuse and the
A/C compressor relay .

Is the action complete?

—

Verify repair

—

1. A/C compressor relay removed.
2. Engine idling.
3. A/C “ON”.
4. Blower “ON”.
5. Use a DVM to measure voltage between the wire at

the A/C compressor relay socket and battery

Did the DVM indicate the specified value?

B+

Go to

Step 32

Go to

Step 29

Check for an open wire between PCM terminal F4 and
the A/C compressor relay.

Was the wire open?

—

Go to

Step 30

Go to

Step 31

Repair the open wire between the PCM and the A/C
compressor relay.

Is the action complete?

—

Verify repair

—

Check for a damaged pin or terminal at F4 of the PCM.

Was a damaged pin or a terminal found?

—

Go to

Step 24

Go to

Step 25

6E–67

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

1. A/C compressor relay removed.
2. Connect a fused jumper at the A/C compressor

relay socket with either wire.

3. Engine idling.
4. A/C “ON”.
5. Blower “ON”.

Did the compressor magnetic clutch engage?

—

Go to

Step 33

Go to

Step 34

Repair the A/C compressor relay.

Is the action complete?

—

Verify repair

—

Check for an open circuit between the A/C compressor
relay and the A/C clutch.

Was an open circuit found?

—

Go to

Step 35

Go to

Step 36

Repair the open circuit between the compressor Clutch
and the A/C compressor relay.

Is the action complete?

—

Verify repair

—

Service the compressor clutch or replace the
compressor due to a faulty internal overheat switch.

Is the action complete?

—

Verify repair

—

1. Remove the A/C compressor relay.
2. Idle the engine.

Is the compressor clutch still engaged when A/C is not
selected?

—

Go to

Step 38

Go to

Step 39

Repair the short to voltage between the A/C clutch and
A/C compressor relay.

Is the action complete?

—

Verify repair

—

1. Reinstall the A/C compressor relay.
2. Remove the A/C thermostat relay.
3. Engine idling.

Is the compressor clutch still engaged when A/C is not
selected?

—

Go to

Step 40

Go to

Step 42

Use a DVM to check for a short to ground between the
A/C compressor relay and F4 of the PCM.

Was a short detected?

—

Go to

Step 41

Go to

Step 25

Repair the short to ground between the PCM and A/C
compressor relay.

Is the action complete?

—

Verify repair

—

Repair the short to ground between the A/C thermostat
relay and the electronic thermostat.

Is the action complete?

—

Verify repair

—

6E–68

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Electronic Ignition System Diagnosis

If the engine cranks but will not run or immediately stalls,
the Engine Cranks But Will Not Start chart must be used
to determine if the failure is in the ignition system or the
fuel system. If DTC P0300 through P0306, P0341, or
P0336 is set, the appropriate diagnostic trouble code
chart must be used for diagnosis.
If a misfire is being experienced with no DTC set, refer to
the

Symptoms section for diagnosis.

EVAP Canister Purge Solenoid and

EVAP Vent Solenoid Valve

A continuous purge condition with no purge commanded
by the PCM will set a DTC P1441. Refer to the DTC charts
for further information.

Visual Check of The Evaporative

Emission Canister

If the canister is cracked or damaged, replace the
canister.

If fuel is leaking from the canister, replace the canister
and check hoses and hose routing.

Fuel Metering System Check

Some failures of the fuel metering system will result in an
“Engine Cranks But Will Not Run” symptom. If this
condition exists, refer to the

Cranks But Will Not Run

chart. This chart will determine if the problem is caused
by the ignition system, the PCM, or the fuel pump
electrical circuit.
Refer to

Fuel System Electrical Test for the fuel system

wiring schematic.
If there is a fuel delivery problem, refer to

Fuel System

Diagnosis, which diagnoses the fuel injectors, the fuel
pressure regulator, and the fuel pump. If a malfunction
occurs in the fuel metering system, it usually results in
either a rich HO2S signal or a lean HO2S signal. This
condition is indicated by the HO2S voltage, which causes
the PCM to change the fuel calculation (fuel injector pulse
width) based on the HO2S reading. Changes made to the
fuel calculation will be indicated by a change in the long
term fuel trim values which can be monitored with a
Tech 2. Ideal long term fuel trim values are around 0%;
for a lean HO2S signal, the PCM will add fuel, resulting in
a fuel trim value above 0%. Some variations in fuel trim
values are normal because all engines are not exactly the
same. If the evaporative emission canister purge is “ON”,
the fuel trim may be as low as –38%. If the fuel trim values
are greater than +23%, refer to

DTC P0131, DTC P0151,

DTC P0171, and DTC 1171 for items which can cause a
lean HO2S signal.

Fuel System Pressure Test

A fuel system pressure test is part of several of the
diagnostic charts and symptom checks. To perform this
test, refer to

Fuel Systems Diagnosis.

Fuel Injector Coil Test Procedure and
Fuel Injector Balance Test Procedure

T32003

Test Description

Number(s) below refer to the step number(s) on the
Diagnostic Chart:
2. Relieve the fuel pressure by connecting the J

34730-1 Fuel Pressure Gauge to the fuel pressure
connection on the fuel rail.

CAUTION: In order to reduce the risk of fire and
personal injury, wrap a shop towel around the fuel
pressure connection. The towel will absorb any fuel
leakage that occurs during the connection of the fuel
pressure gauge. Place the towel in an approved
container when the connection of the fuel pressure
gauge is complete.

Place the fuel pressure gauge bleed hose in an
approved gasoline container.
With the ignition switch “OFF”, open the valve on the
fuel pressure gauge.

3. Record the lowest voltage displayed by the DVM

after the first second of the test. (During the first
second, voltage displayed by the DVM may be
inaccurate due to the initial current surge.)

Injector Specifications:

Resistance (Ohms)

Voltage Specification at

C-35

C (50

F-95

11.8 – 12.6

5.7 – 6.6

The voltage displayed by the DVM should be within
the specified range.

The voltage displayed by the DVM may increase
throughout the test as the fuel injector windings
warm and the resistance of the fuel injector windings
changes.

6E–69

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

An erratic voltage reading (large fluctuations in
voltage that do not stabilize) indicates an
intermittent connection within the fuel injector.

5. Injector Specifications:

Highest Acceptable

Voltage Reading

Above/Below 35

C/10

(95

F/50

Acceptable Subtracted

Value

9.5 Volts

0.6 Volts

7. The Fuel Injector Balance Test portion of this chart

(Step 7 through Step 11) checks the mechanical
(fuel delivery) portion of the fuel injector. An engine
cool-down period of 10 minutes is necessary in
order to avoid irregular fuel pressure readings due
to “Hot Soak” fuel boiling.

Injector Coil Test Procedure (Steps 1-6) and Injector Balance Test Procedure

(Steps 7-11)

R262001

CYLINDER

1st Reading (1)

296 kPa

(43 psi)

296 kPa

(43 psi)

296 kPa

(43 psi)

296 kPa

(43 psi)

296 kPa

(43 psi)

296 kPa

(43 psi)

2nd Reading (2)

131 kPa

(19 psi)

117 kPa

(17 psi)

124 kPa

(18 psi)

145 kPa

(21 psi)

131 kPa

(19 psi)

130 kPa

(19 psi)

Amount of Drop (1st

Reading–2nd Reading)

165 kPa

(24 psi)

179 kPa

(26 psi)

172 kPa

(25 psi)

151 kPa

(22 psi)

165 kPa

(24 psi)

166 kPa

(24 psi)

Av.drop = 166 kPa/24 psi

10 kPa/1.5 psi

= 156 – 176 kPa or

22.5 – 25.5 psi

Faulty, Rich

(Too Much

Fuel Drop)

Faulty, Lean

(Too Little

Fuel Drop)

NOTE: These figures are examples only.

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