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Opel Frontera UE. Manual - part 1462

6E–63

6VD1 3.2L 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

—

SECTION

6E–64

6VD1 3.2L 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.

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.

Powertrain Control Module (PCM)

Diagnosis

To read and clear diagnostic trouble codes, use a Tech 2.
IMPORTANT:

Use of a Tech 2 is recommended to clear

diagnostic trouble codes from the PCM memory.
Diagnostic trouble codes can also be cleared by turning
the ignition “OFF” and disconnecting the battery power
from the PCM for over 3 hours. Turning off the ignition
and disconnecting the battery power from the PCM will
cause all diagnostic information in the PCM memory to be
cleared. Therefore, all the diagnostic tests will have to be
re-run.
Since the PCM can have a failure which may affect only
one circuit, following the diagnostic procedures in this

section will determine which circuit has a problem and
where it is.
If a diagnostic chart indicates that the PCM connections
or the PCM is the cause of a problem, and the PCM is
replaced, but this does not correct the problem, one of the
following may be the reason:

There is a problem with the PCM terminal
connections. The terminals may have to be removed
from the connector in order to check them properly.

EEPROM program is not correct for the application.
Incorrect components or reprogramming the PCM
with the wrong EEPROM program may cause a
malfunction and may or may not set a DTC.

The problem is intermittent. This means that the
problem is not present at the time the system is being
checked. In this case, refer to the

Symptoms portion

of the manual and make a careful physical inspection
of all component and wiring associated with the
affected system.

There is a shorted solenoid, relay coil, or harness.
Solenoids and relays are turned “ON” and “OFF” by
the PCM using internal electronic switches called
drivers. A shorted solenoid, relay coil, or harness will
not damage the PCM but will cause the solenoid or
relay to be inoperative.

Multiple PCM Information Sensor

DTCs Set

Circuit Description

The powertrain control module (PCM) monitors various
sensors to determine the engine operating conditions.
The PCM controls fuel delivery, spark advance,
transmission operation, and emission control device
operation based on the sensor inputs.
The PCM provides a sensor ground to all of the sensors.
The PCM applies 5 volts through a pull–up resistor, and
determines the status of the following sensors by
monitoring the voltage present between the 5–volt supply
and the resistor:

The engine coolant temperature (ECT) sensor

The intake air temperature (IAT) sensor

The transmission fluid temperature (TFT) sensor

The PCM provides the following sensors with a 5–volt
reference and a sensor ground signal:

The exhaust gas recirculating (EGR) pintle position
sensor

The manifold absolute pressure (MAP) sensor

The throttle position (TP) sensor 1

The accelerator position (AP) sensor 1

The accelerator position (AP) sensor 3

The Crank position (CKP) sensor

The throttle position (TP) sensor 2

The accelerator position (AP) sensor 2

SECTION

6E–65

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

The PCM monitors the separate feedback signals from
these sensors in order to determine their operating
status.

Diagnostic Aids

IMPORTANT:

Be sure to inspect PCM and engine

grounds for being secure and clean.
A short to voltage in one of the sensor input circuits may
cause one or more of the following DTCs to be set:

P0108, P1106

P0406

P1120, P1515, P1221, P1516, P1635

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272

IMPORTANT:

If a sensor input circuit has been shorted

to voltage, ensure that the sensor is not damaged. A
damaged sensor will continue to indicate a high or low
voltage after the affected circuit has been repaired. If the
sensor has been damaged, replace it.
An open in the sensor ground circuit between the PCM
and the splice will cause one or more of the following
DTCs to be set:

P0108, P1106

P0406

P1120, P1515, P1221, P1516, P1635

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272

A short to ground in the 5–volt reference A or B circuit will
cause one or more of the following DTCs to be set:

P0106, P0107, P1107

P0401, P1404, P0405

P1120, P1515, P1221, P1516, P1635

P1275, P1639, P1271, P1273

P1285, P1272, P1273

P0336, P0337

P1220, P1515, P1221, P1515, P1516

P1280, P1271, P1272

Check for the following conditions:

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

Damaged harness. Inspect the wiring harness for
damage. If the harness is not damaged, observe an
affected sensor fs displayed value on the Tech 2 with
the ignition “ON” and the engine “OFF” while you
move the connectors and the wiring harnesses
related to the following sensors:

MAP Sensor

EGR

TPS1/TPS2

APS1/APS2/APS3

CKP

SECTION

6E–66

6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Multiple PCM Information Sensor DTCs Set

Step

Action

Value(s)

Yes

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

—

Go to

Step 2

Go to

OBD

System

Check

1. Turn the ignition “OFF”, disconnect the PCM.
2. Turn the ignition “ON”, check the 5 volt reference 1

and 2 circuit for the following conditions:

A poor connection at the PCM.

An open between the PCM connector and the
splice.

A short to ground.

A short to voltage.

Is there an open or short?

—

Go to

Step 3

Go to

Step 4

Repair the open or short.

Is the action complete?

—

Verify repair

—

Check the sensor ground circuit for the following
conditions:

A poor connection at the PCM or the affected
sensors.

An open between the PCM connector and the
affected sensors.

Is there an open or a poor connection?

—

Go to

Step 5

Go to

Step 6

Repair the open or the poor connection.

Is the action complete?

—

Verify repair

—

Following below the DTCs stored:
P1635, P1639

—

Go to

applicable
DTC table

Go to

Step 7

Measure the resistance below the items:

EGR sensor supply circuit and ground circuit.

Between MAP sensor supply circuit and EGR
Sensor supply circuit.

Between MAP Sensor supply circuit and PCM
harness connector. (5Volt supply circuit)

Is the resistance near the specified value?

Go to

Step 9

Go to

Step 8

Locate and repair the open circuit in the MAP or EGR
sensor supply circuit.

Is the action complete?

—

Verify repair

—

1.  Disconnect the MAP, and EGR connector.
2.  Ignition “ON”.
3.  Measure the resistance below the items:

MAP sensor GND circuit.

EGR GND circuit.

Does the voltage resistance near the specified value?

Go to

Step 11

Go to

Step 10

Locate and repair the short circuit in the MAP or EGR
sensor signal or GND circuit.

Is the action complete?

—

Verify repair

—

SECTION

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