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Opel Frontera UBS. Manual - part 288

6E–58

ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

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

wires at the A/C compressor relay socket.

Is the voltage equal to the specified value?

Go to

Step 36

Go to

Step 35

Repair the faulty BRN 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

GRN/BLK wire at the A/C compressor relay socket
and battery

Did the DVM indicate the specified value?

Go to

Step 40

Go to

Step 37

Check for an open GRN/BLK wire between PCM
terminal B-14 and the A/C compressor relay.

Was the wire open?

—

Go to

Step 38

Go to

Step 39

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

Is the action complete?

—

Verify repair

—

Check for a damaged pin or terminal at B-14 of the
PCM.

Was a damaged pin or a terminal found?

—

Go to

Step 32

Go to

Step 33

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

relay socket between either BRN wire and the
BRN/YEL wire.

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

Did the compressor magnetic clutch engage?

—

Go to

Step 41

Go to

Step 42

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 43

Go to

Step 44

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

—

6E–59

ENGINE DRIVEABILITY AND EMISSIONS

A/C Clutch Control Circuit Diagnosis

(Cont'd)

Step

Yes

Value(s)

Action

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 46

Go to

Step 47

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 48

Go to

Step 50

Use a DVM to check for a short to ground between the
A/C compressor relay and B-14 of the PCM.

Was a short detected?

—

Go to

Step 49

Go to

Step 33

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–60

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 the ignition system or the fuel
system. If DTC 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.

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 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.

Idle Air Control (IAC) Valve

The Tech 2 displays the IAC pintle position in counts. A
count of “0” indicates the PCM is commanding the IAC
pintle to be driven all the way into a fully-seated position.
This is usually caused by a large vacuum leak.
The higher the number of counts, the more air is being
commanded to bypass the throttle blade. Refer to IAC
System Check in order to diagnose the IAC system.
Refer to

Rough, Unstable, or Incorrect Idle, Stalling in

Symptoms for other possible causes of idle problems.

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

5-8840-0378-0 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–61

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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