1998 OPEL FRONTERA engine

6E–52
ENGINE DRIVEABILITY AND EMISSIONS
10.This vehicle is equipped with a PCM which utilizes
an electrically erasable programmable read only
memory (EEPROM). When the PCM is replaced,
the new PCM must be programmed.
Refer to UBS
98 model year Immobilizer Workshop Manual.

6E–53 ENGINE DRIVEABILITY AND EMISSIONS
On-Board Diagnostic (OBD) System Check
StepActionVa l u e ( s )Ye sNo
11. Ignition “ON,” engine “OFF.”
2. Observe the malfunction indicator lamp (MIL or
“Check Engine” lamp).
Is the MIL (“Check Engine” lamp)“ON?”
—Go to Step 2
Go to No MIL
(“Check
Engine” lamp)
21. Ignition “OFF.”
2. Install a Tech 2.
3. Ignition “ON.”
4. Attempt to display PCM engine data with the Tech 2.
Does the Tech 2 display PCM data?
—Go to Step 3Go to Step 8
31. Using the Tech 2 output tests function, select MIL
(“Check Engine” lamp) dash lamp control and
command the MIL (“Check Engine” lamp) “OFF.”
2. Observe the MIL (“Check Engine” lamp).
Did the MIL (“Check Engine” lamp) turn “OFF?”
—Go to Step 4
Go to MIL
(“Check
Engine” lamp)
On Steady
4Attempt to start the engine.
Did the engine start and continue to run?
—Go to Step 5
Go to Cranks
But Will Not
Run
5Select “Display DTCs” with the Tech 2.
Are any DTCs stored?
—Go to Step 6Go to Step 7
6Are two or more of the following DTCs stored? P0107,
P0108, P0113, P0118, P0122, P0123, P0712.?
—
Go to
“Multiple
PCM
Information
Sensor DTCs
Set”
Go to
applicable
DTC table
7Compare PCM data values displayed on the Tech 2 to
the typical engine scan data values.
Are the displayed values normal or close to the typical
values?
—
Refer
to
Ty p i c a l
scan data
value
Refer to
indicated
Component
System
Checks
81. Ignition “OFF,” disconnect the PCM.
2. Ignition “ON,” engine “OFF.”
3. Check the Class 2 data circuit for an open, short to
ground, or short to voltage. Also, check the DLC
ignition feed circuit for an open or short to ground
and the DLC ground circuit for an open.
4. If a problem is found, repair as necessary.
Was a problem found?
—Go to Step 2Go to Step 9
9Attempt to display PCM data with the Tech 2.
Does the Tech 2 display PCM engine data?
—Go to Step 2Go to Step 10
10Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
Powertrain Control Module
(PCM) in On-Vehicle Service.
Is the action complete?—Go to Step 2—

6E–54
ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
D06RW085
Circuit Description
When air conditioning and blower fan are selected, and if
the system has a sufficient refrigerant charge, a 12-volt
signal is supplied to the A/C request input of the
powertrain control module (PCM). The A/C request
signal may be temporarily canceled during system
operation by the electronic thermostat in the evaporator
case. The electronic thermostat may intermittently
remove the control circuit ground for the A/C thermostat
relay to prevent the evaporator from forming ice. When
the A/C request signal is received by the PCM, the PCM
supplies a ground from the compressor clutch relay if the
engine operating conditions are within acceptable
ranges. With the A/C compressor relay energized,
voltage is supplied to the compressor clutch coil.
The PCM will enable the compressor clutch to engage
whenever A/C has been selected with the engine running,
unless any of the following conditions are present:
The throttle is greater than 90%.
The ignition voltage is below 10.5 volts.
The engine speed is greater than 4500 RPM for 5
seconds or 5400 RPM.
The engine coolant temperature (ECT) is greater than
125
C (257 F).
The intake air temperature (IAT) is less than 5C
(41
F).
The power steering pressure switch signals a cramped
position.
Diagnostic Aids
To diagnose an the intermittent fault, check for the
following conditions:
Poor connection at the PCM–Inspect connections for
backed-out terminals, improper mating, broken locks,
improperly formed or damaged terminals, and poor
terminal-to-wire connection.

6E–55 ENGINE DRIVEABILITY AND EMISSIONS
Damaged harness–Inspect the wiring harness for
damage. If the harness appears to OK, observe the
A/C clutch while moving connectors and wiring
harnesses related to the A/C. A sudden clutch
malfunction will indicate the source of the intermittent
fault.
A/C Clutch Diagnosis
This chart should be used for diagnosing the electrical
p o r t i o n o f t h e A / C c o m p r e s s o r c l u t c h c i r c u i t . A Te c h 2 w i l l
be used in diagnosing the system. The Tech 2 has the
ability to read the A/C request input to the PCM. The Tech
2 can display when the PCM has commanded the A/C
clutch “ON.” The Tech 2 should have the ability to
override the A/C request signal and energize the A/C
compressor relay.
Test Description
IMPORTANT:Do not engage the A/C compressor
clutch with the engine running if an A/C mode is not
selected at the A/C control switch.
The numbers below refer to the step numbers on the
Diagnostic Chart:3. This a test determine is the problem is with the
refrigerant system. If the switch is open, A/C
pressure gauges will be used to determine if the
pressure switch is faulty or if the system is partially
discharged or empty.
4. Although the normal complaint will be the A/C clutch
failing to engage, it is possible for a short circuit to
cause the clutch to run when A/C has not been
selected. This step is a test for that condition.
7. There is an extremely low probability that both relays
will fail at the same time, so the substitution process
is one way to check the A/C Thermostat relay. Use
a known good relay to do a substitution check.
9. The blower system furnishes a ground for the A/C
control circuit, and it also shares a power source
through the Heater and A/C Relay. The blower
must be “ON” in order to test the A/C system.
A/C Clutch Control Circuit Diagnosis
StepActionVa l u e ( s )Ye sNo
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2
Go to OBD
System
Check
2Are any other DTCs stored?
—
Go to the
other DTC
chart(s) first
Go to Step 3
31. Disconnect the electrical connector at the pressure
switch located on the receiver/drier.
2. Use an ohmmeter to check continuity across the
pressure switch.
Is the pressure switch open?
—
Go to Air
Conditioning
to diagnose
the cause of
the open
pressure
switch
Go to Step 4
4IMPORTANT:Before continuing with the diagnosis, the
following conditions must be met:
The intake air temperature must be greater than
15
C. (60F).
The engine coolant temperature must be less
than 119
C (246F).
1. A/C “OFF.”
2. Start the engine and idle for 1 minute.
3. Observe the A/C compressor.
Is the A/C compressor clutch engaged even though
A/C has not been requested?
—Go to Step 45Go to Step 5
51. Idle the engine.
2. A/C “ON”.
3. Blower “ON”.
4. Observe the A/C compressor.
Is the A/C compressor magnetic clutch engaged?
—
Refer to
Diagnostic
Aids
Go to Step 6

6E–56
ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
StepNo Ye s Va l u e ( s ) Action
61. Engine idling.
2. A/C “ON”.
3. Blower “ON”.
4. Observe the “A/C Request” display on the Tech 2.
Does the tool “A/C Request” display indicate “Yes?”
—Go to Step 34Go to Step 7
7Temporarily substitute the A/C compressor relay in
place of the A/C thermostat relay, then repeat Step 5.
Did the “A/C Request” display indicate “Yes?”
—Go to Step 8Go to Step 9
8Replace the original A/C thermostat relay.
Is the action complete?
—Verify repair—
9Dose the blower operate?—Go to Step 10Go to Step 11
10Repair the blower.
Is the action complete?
—Verify repair—
11Check for a faulty 10a A/C fuse in the underdash fuse
panel.
Was the 10A fuse OK?
—Go to Step 13Go to Step 12
12Check for short circuit and make repairs if necessary.
Replace the 10A A/C fuse.
Is the action complete?
—Verify repair—
131. Ignition “ON.”
2. Use a DVM to check voltage at the positive A/C
switch wire (BRN).
Was voltage equal to the specified value?
+BGo to Step 15Go to Step 14
14Repair the open wire (BRN) between the A/C switch
and the A/C fuse.
Is the action complete?
—Verify repair—
151. Remove the glove box to gain access to the A/C
thermostat.
2. Disconnect the thermostat connector.
3. Attach a fused jumper between ground and the
PNK/GRN wire at the thermostat.
4. A/C “ON.”
5. Blower “ON.”
Dose A/C request indicate “YES” on the Tech 2?
—Go to Step 16Go to Step 23
161. Ignition “ON.”
2. Use a DVM to check voltage at the electronic A/C
thermostat.
Was voltage equal to the specified value?
+BGo to Step 20Go to Step 17
17Check for an open (LT GRN) between the thermostat
and the A/C switch.
Was the wire open?
—Go to Step 18Go to Step 19
18Repair the open wire (LT GRN) between the thermostat
and the A/C switch.
Is the action complete?
—Verify repair—

6E–57 ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
StepNo Ye s Va l u e ( s ) Action
19Replace the A/C switch.
Is the action complete?
—Verify repair—
20Use an ohmmeter to check continuity between the
electronic A/C thermostat and the blower switch.
Was there an open circuit?
—Go to Step 21Go to Step 22
21Repair the open wire (GRN/YEL) between the
thermostat and the blower switch.
Is the action complete?
—Verify repair—
22Replace the electronic A/C thermostat.
Is the an action complete?
—Verify repair—
23Check for an open circuit between A/C thermostat relay
and PCM A/C request terminal (E-15).
Was there an open circuit?
—Go to Step 24Go to Step 25
24Repair the open circuit between the PCM and A/C
thermostat relay.
Is the action complete?
—Verify repair—
25Check for an open circuit between the A/C switch (LT
GRN) and the A/C thermostat relay (LT GRN).
Was there an open circuit?
—Go to Step 26Go to Step 27
26Repair the open circuit between the A/C switch and the
A/C thermostat relay.
Is the action complete?
—Verify repair—
271. Ignition “ON.”
2. Use a DVM to check voltage at the A/C pressure
switch (BRN).
Was voltage equal to the specified value?
+BGo to Step 29Go to Step 28
28Repair the open circuit between the 10A A/C fuse and
the pressure switch.
Is the action complete?
—Verify repair—
29Use an ohmmeter to check continuity between the
pressure switch (GRN/WHT) and the A/C thermostat
relay (GRN/WHT).
Was the circuit open?
—Go to Step 30Go to Step 31
30Repair the open circuit between the pressure switch
and the A/C thermostat relay.
Is the action complete?
—Verify repair—
31Check for damaged pin or terminal at E-15 of the PCM.
Was a damaged pin or terminal found?
—Go to Step 32Go to Step 33
32Repair the damaged pin or terminal.
Is the action complete?
—Verify repair—
33Replace the PCM.
IMPORTANT:The replacement PCM must be
programmed. Refer to
UBS 98model year Immobilizer
Workshop Manual.
Is the action complete?—Verify repair—

6E–58
ENGINE DRIVEABILITY AND EMISSIONS
A/C Clutch Control Circuit Diagnosis
StepNo Ye s Va l u e ( s ) Action
341. 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?
+BGo to Step 36Go to Step 35
35Repair the faulty BRN wire between the A/C fuse and
the A/C compressor relay .
Is the action complete?
—Verify repair—
361. 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?
+BGo to Step 40Go to Step 37
37Check for an open GRN/BLK wire between PCM
terminal B-14 and the A/C compressor relay.
Was the wire open?
—Go to Step 38Go to Step 39
38Repair the open GRN/BLK wire between the PCM and
the A/C compressor relay.
Is the action complete?
—Verify repair—
39Check for a damaged pin or terminal at B-14 of the
PCM.
Was a damaged pin or a terminal found?
—Go to Step 32Go to Step 33
401. 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 41Go to Step 42
41Repair the A/C compressor relay.
Is the action complete?
—Verify repair—
42Check for an open circuit between the A/C compressor
relay and the A/C clutch.
Was an open circuit found?
—Go to Step 43Go to Step 44
43Repair the open circuit between the compressor Clutch
and the A/C compressor relay.
Is the action complete?
—Verify repair—
44Service 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
StepNo Ye s Va l u e ( s ) Action
451. 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 46Go to Step 47
46Repair the short to voltage between the A/C clutch and
A/C compressor relay.
Is the action complete?
—Verify repair—
471. 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 48Go to Step 50
48Use 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 49Go to Step 33
49Repair the short to ground between the PCM and A/C
compressor relay.
Is the action complete?
—Verify repair—
50Repair the short to ground between the A/C thermostat
relay and the electronic thermostat.
Is the action complete?
—Verify repair—