1987 NISSAN PULSAR warning light

Roadside Trouble Shooting
(5) Place the vent caps loosely over the cell
apertures.

(6) Connect one end of the red jumper lead to
the positive ( + ) battery terminal of the booster
battery and the other end of the red lead to the
positive (+) battery terminal of the discharged bat-
tery.

NOTE: The battery emits hydrogen gas
which is explosive. Do not expose the battery
to naked /lames or sparks.

Do not lean over the battery when con-
necting the jumper leads.

Do not allow the ends of the jumper leads
to touch one another or any part of the
engine.

(7) Connect one end of the black juniper lead to
the negative (-) battery terminal of the booster
battery and the other end of the black lead to a good
earthing point on the engine of the vehicle with the
discharged battery.

NOTE: Do not connect the jumper lead
directly to the negative (-) battery terminal
of the discharged battery.

(8) Start the engine on the vehicle with the
booster battery and run the engine at a moderate
speed. (9) Start the engine on the vehicle with the
discharged battery.
(10) If possible, leave the engines of both vehi-
cles running for 10 minutes.
(11) Disconnect the jumper leads in the reverse
order of the sequence in which they were connected.
2. TO CHECK IGNITION AND ELECTRICAL SYSTEM

(1) Switch on the ignition and check for warning
lamp illumination on the dashboard. (2) Operate the starter and check that the starter
rotates the engine at a steady speed.
(3) Switch on the headlamps and check for good
light intensity. Should the lamps not illum inate or the starter
motor not turn the engine, carry out the following
steps:

(a) Remove the battery terminals and clean both
terminals and posts. Connect the terminals and where
applicable tighten firmly but not excessively.
(b) Check that the earth lead from the battery to
the engine or body frame is not broken and that the
connections are clean and secure. . (c) Check that the lead from the battery to the
starter motor or starter solenoid is intact and has a
clean and secure connection.


Ensure that the battery posts and terminals are clean.
(d) Where necessary carry out repairs to (b) and
(c).

Repeat the check procedur e. Should the starter
motor still not operate, or the lamps not illuminate,
one or more of the following faults may be the cause:

No starter motor operation or lamps: Battery flat
or defective.

Lamps illuminate but no starter operation: Starter
motor drive jammed in mesh with flywheel ring gear.
Starter motor or solenoid defective. Ignition/starter
switch faulty. On automatic transaxle models, faulty
neutral safety switch.

Lamps dim and starter operation sluggish: Dis-
charged battery or fault in starter motor. Battery flat
due to broken fan belt or de fective alternator. Faulty
battery due to cell breakdown.

NOTE: Electronic ignition systems can pro-
duce dangerously high voltages in both the
primary and secondary circuits. For this
reason, extreme care must be taken when
performing these checks. When disconnect-


Securely earth the body of a test spark plug to check
for sparks at the spark plug leads.

Fuel and Engine Management 89
The procedure for fabricating an LED test lamp is
fully described in the El ectrical System section.

If a conventional test lamp with a filament type
bulb is to be used, ensure that the current draw of the
test lamp does not exceed 0.3 amp to avoid damage to
the electronic components.

To check the current draw connect an accurate
ammeter, such as the multimeter described previ-
ously, in series with the test lamp and a battery.

If the ammeter reads less than 0.3 amp the test
lamp is suitable.

Tachometer
(1) Disconnect the resistor from the tachometer
pick-up wiring connector which is located on the
ignition coil wiring harness, and connect the positive
lead of an accurate tachometer to the brown wire
terminal in the wiring connector. (2) Connect the negative lead to a good earthing
point.

View showing the location of the tachometer pickup
wiring connector with the resistor installed.
Timing Light
(1) Connect the timing light to the engine fol-
lowing the instrument manufacturers instructions.

NOTE: Do not connect or disconnect the
timing light with the engine running as
voltage surges could damage the alternator
or control unit. Do not allow the high
tension leads to open circuit with the engine
running as damage to the engine manage-
ment system could result.

(2) Do not connect the timing light positive lead
to the alternator output terminal. Where possible,
connect the power leads of the timing light to an
external power source to prevent possible transient
voltages damaging the alternator or control unit.

4. SYSTEM DIAGNOSIS AND ADJUSTMENTS
NOTE: Due to the use of complex electronic
components in the engine management sys-

tem, the diagnosis and testing procedures
described in this section should not be
carried out by persons lacking an under-
standing of electronics and the precautions
associated with the servicing of electronic
components. It is rec ommended that should
a fault arise in the system, the vehicle be
referred to an authorized workshop.

The control unit can be damaged by
component faults not indicated by the self
diagnosis codes and the renewal of the
control unit without lo cating the cause of
the failure will result in the failure of the
replacement unit. It is for this reason that
the practice of substituting components to
isolate faults is not recommended.

Prior to performing any of the follow-
ing operations, refer to the Service Pre-
cautions and Procedures heading.

PRELIMINARY CHECKS
Prior to performing the Self Diagnosis Test Pro-
cedures, perform the following preliminary checks and
rectify any problems as necessary.

(1) Check for an adequate supply of fuel in the
fuel tank. (2) Check the wiring connectors and earth points
of all engine management components for clean,
secure connections. To prevent damage to the control
unit, disconnect the negative battery terminal before
disconnecting any engine ma nagement wiring connec-
tors. (3) Check the condition of the battery. Refer to
the Electrical System sectio n for checking procedures.
Rectify any faults as necessary. (4) Check the air cleaner element for restriction.
(5) Check for air leaks at the throttle body, inlet
manifold and all related hoses. (6) Check the fuel pump pr essure as described
later in this section. (7) Ensure that the engine is in a satisfactory
mechanical condition and is in tune. Refer to the
Engine and Engine Tune-up sections as necessary.
SELF DIAGNOSIS

This function is very useful in locating system
faults particularly intermittent problems. However,
the self diagnosis mode does not provide comprehen-
sive testing of the engine management system, and
therefore should always be used in conjunction with
the other test procedures described later, in order to
accurately locate system faults.

To Interpret Self Diagnosis Codes
Once the self diagnosis mode is activated, various
fault codes will be displayed as a series of flashes by
the ECM warning lamp on the instrument cluster.

\(V2 Fuel and Engine Management


View of the IAC valve removed from the engine. Dimension A must not exceed 28 mm.
(3) Lubricate the IAC valve O ring with engine
oil and install the IAC valve. Tighten the retaining
screws securely.

(4). Install the IAC valve wiring connector and
the negative battery terminal.

(5) On 1.6 liter engines, install the air cleaner
assembly as previously described. (6) Run the engine until normal operating tem-
perature and idle speed are attained.
NOTE: Several minutes may elapse before
the normal idle speed is attained.

(7) Hold the throttle open at approximately
3 000 rpm for 10 seconds to reset the IAC valve.

MANIFOLD ABSOLUTE PRESSURE (MAP)
SENSOR

To Test - Codes 33 and 34
NOTE: The following test procedure
assumes that fault codes 33 or 34 have
been
displayed during the self diagnosis test
pro-
cedure. If no codes have been displayed
but
the operation of the MAP sensor is suspect,
begin the test procedure at operation (15).
(1) Erase the self diagnosis code memory as
previously described.
(2) Start and run the engine at idle speed for 60
seconds or until the ECM warning lamp lights.
(3) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connector. Note any fault codes
displayed. If code 34 is displayed, remove the jumper lead
from the diagnostic link connector, erase the self
diagnosis codes and proceed to operation (7).

If code 33 is displayed, remove the jumper lead
from the diagnostic link connector, erase the self
diagnosis code memory and proceed to operation (4).

If no codes are displayed, but codes 33 or 34
were
displayed when the self diagnosis test procedure was
originally performed, an intermittent fault is indi-
cated. Proceed as follows:

(a) Check for faulty wiring connections. Check
that all wiring connectors are clean and secure. (b) Check that all earth wires are secure.
(c) Check the vacuum hose to the MAP sensor
for deterioration or restriction.
(4) Disconnect the wiring connector from the
MAP sensor. (5) Start and run the engine at idle speed for 60
seconds or until the ECM warning lamp lights. (6) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connector. Note any fault codes
displayed.
If code 33 is displayed, measure the voltage at
the
MAP sensor wiring connector terminal B with a
voltmeter to earth. Renew the control unit if the
voltage is less than 1 volt.

If the voltage is more than 1 volt, check the
wiring
harness for a short to voltage between terminal B and
the control unit wiring connector terminal Cll.
Repair or renew the wiring harness as necessary.

If code 34 is displayed, proceed as follows:
(a) Check for a restricted or leaking MAP sensor
vacuum hose.
(b) Check the wiring harness for continuity and
shorts between terminals A on the MAP sensor
connector and terminal A11 on the control unit wiring
connector. Repair or renew the wiring harness as
necessary.
If no faults are indicated in the above two checks,
proceed to operation (15).

(7) Disconnect the wiring connector from the
MAP sensor and connect a jumper lead between
terminals B and C on the wiring connector. (8) Start and run the engine at idle speed for 60
seconds or until the ECM warning lamp lights. (9) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connector. Note any fault codes
displayed.
If code 33 is displayed, proceed to operation (15).
If code 34 is displayed, proceed as follows.

Location of the MAP sensor. Inset shows the terminal
identification.

106 Fuel and Engine Management
on the pickup coil wiring connector. The resistance
should be 500-1 500 ohms.

If the resistance is not as specified in either of the
above tests, renew the pickup coil.

(4) Remove the retaining spring from the dis-
tributor drive coupling.
(5) Using a pin punch, remove the drive pin
from the shaft. (6) Remove the drive coupling, washer, tang
washer and thrust spring from the shaft. (7) Remove the rotor and sh aft from the distrib-
utor housing. (8) Remove the retainer from the distributor
housing and withdraw the pickup coil. (9) Remove the retaining sc rews and remove the
control module from the distributor body. (10) Carefully lever the stationary pole from the
housing using a suitable screwdriver. Assembly is a reversal of the dismantling proce-
dure with attention to the following points:

(1) Ensure that the mating surfaces of the dis-
tributor housing and the control module are clean.
(2) Apply a silicone heat sink compound to the
surfaces between the control module and the distrib-
utor housing.
IGNITION COIL

To Test
(1) Disconnect the grey wiring connector and the
black wiring connector from the ignition coil in that
order. (2) Measure the resistance between coil terminal
I and the coil body. There should be a high resistance. (3) Measure the resistance between coil termi-
nals 2 and 4. There should be a low resistance. (4) Measure the resistance between coil terminal
3 and the high tension termin al. The resistance should
be other than infinity.
If any of the tests indicate a fault, renew the
ignition coil.

To Remove and Install
(1) Disconnect the negative battery terminal.
(2) Disconnect the grey wiring connector and the
black wiring connector from the ignition coil in that
order. Disconnect the high tension lead. (3) Remove the coil mounting bracket retaining
bolts and remove the coil and bracket from the
engine. Installation is a reversal of the removal procedure.

ELECTRONIC SPARK TIMING
To Test - Code 42

(1) Erase the self diagnosis code memory as
previously described. (2) Start and run the engine at idle speed for 60
seconds or until the ECM warning lamp lights.
(3) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connector . Note any fault codes
displayed. If code 42 is displayed, proceed to operation (4).

If code 42 is not displayed, but was displayed
when the self diagnosis test procedure was originally
performed, an intermittent fault is indicated. Proceed
as follows:

(a) Check for faulty wiri ng connections. Check
that all wiring connectors are clean and secure.
(b) Check that all earth wires are secure.
(4) With the ignition switched Off, disconnect
the control unit wiring connectors. (5) With the ignition switched On, measure the
resistance between the contro l unit wiring connector
terminal D4 and a good earthing point. The resistance
should be less than 500 ohms.
If the ohmmeter reading is as specified, check the
wiring harness between the distributor 4 pin wiring
connector terminal D and the control unit wiring
connector terminal D4 for continuity. Repair or
renew the wiring harness as necessary. Also ensure
that the distributor 4 pin wiring connector is making
good contact when connected to the distributor.

If no fault can be found, renew the ignition
control module.

If the resistance is as specified proceed as follows.
(6) With the lead of a test lamp connected to the
positive battery terminal, backprobe the control unit
wiring connector terminal D5.

If the test lamp does not light, proceed to
operation (7).

If the test lamp lights, disconnect the 4 pin wiring
connector from the distributor. If the test lamp
remains illuminated check the wiring harness between
the distributor 4 pin wiring connector terminal B and
the control unit wiring connector terminal D5 for
shorts to earth. Repair or renew the wiring harness as
necessary. If the test lamp extinguishes, renew the
ignition system control module.

(7) Connect an ohmmeter between the control
Installed view of the ignition coil showing the coil
terminal identification.

Fuel and Engine Management 107
unit wiring connector terminal D4 and a good earth-
ing point.

(8) With the lead of a test lamp connected to the
positive battery terminal, backprobe the control unit
wiring connector terminal D5. As the test lamp probe
touches the terminal, the ohmmeter reading should
change from less than 500 ohms to over 5 000 ohms.

If the ohmmeter reading is not as specified,
proceed to operation (9).

If the ohmmeter reading is as specified, switch the
ignition Off and install the control unit wiring connec-
tors. Run the engine for 60 seconds or until the ECM
warning lamp lights and check for fault codes.

If code 42 is displayed renew the control unit.
If code 42 is not displayed, check the wiring
harness for continuity or sh orts between the control
unit wiring connector terminals D4 and D5 and the
distributor 4 pin wiring connector terminals D and B.

(9) Disconnect the 4 pin wiring connector from
the distributor.

(10) Check for continuity between the control
unit wiring connector termin al D4 and a good earth-
ing point. There should be no continuity.

If the continuity is not as specified, check the
wiring harness between the distributor 4 pin wiring
connector terminal D and the control unit wiring
connector terminal D4 for shorts to earth. Repair or
renew the wiring harness as necessary.

If the continuity is as specified, check the wiring
harness between the distributor 4 pin wiring connec-
tor terminal B and the control unit wiring connector
terminal D5 for continuity. Repair or renew the
wiring harness as necessary. If no fault is found, renew
the ignition system control module.

CONTROL UNIT
To Test Input Circuits — Code 55
(1) Switch the ignition On with the engine
stopped and note the ECM warning lamp. (2) If a steady light is showing, proceed to
operation (3). If code 55 is displayed, proceed as follows:

(a) Switch the ignition Off and disconnect the
wiring connector from the control unit.
(b) Switch the ignition On and measure the
voltage at the wiring connector on terminals C10,
C I 1 , C12, C13 and A9. Disregard terminal C12 on
1.6 liter engines. (c) If there is voltage at any of the terminals
tested above, a faulty wi ring harness is indicated.
Repair the short circuit to voltage and return to
operation (1). (d) If there is no voltage at any of the terminals
tested, a faulty control unit is indicated. Renew the
control unit and return to operation ( 1 ) . (3) Connect a jumper lead between terminals A
and B on the diagnostic link connector and note if
code 55 is displayed.

If code 55 is displayed, an intermittent fault is
indicated. Switch Off the engine, erase the self diag-
nosis codes and run the engine for 2 minutes. Return
to operation (1 ) and repeat the test procedures.

If code 55 continues to return, renew the control
unit.

To Remove and Install
(1) Disconnect the negative battery terminal.
(2) Slide the passengers front seat to the rear-
most position and working under the seat, disconnect
the control unit wiring connectors. (3) Disengage the plastic control unit cover from
the mounting plate and remove the control unit from
the vehicle. (4) If necessary, remove the screws retaining the
Mem-Cal cover to the control unit.
(5) Release the Mem-Cal unit retaining clips,
grasp the Mem-Cal unit at each end and remove it
from the control unit. Installation is a reversal of the removal procedure
with attention to the following points:

(1) When installing the Mem-Cal unit, align the
notches in the Mem-Cal with those in the control unit
and push on each end of the Mem-Cal unit. Do not
push on the middle section of the Mem-Cal unit.

View of the control unit with the Mem-Cal unit re-
moved.

Fuel and Engine Management 109


Diagram showing the identification of the relay and the relay connector terminals.
To Test Relay Circuits
(1) Remove the relevant relay as previously
described and connect the ne gative battery terminal.
(2) Connect a test lamp to earth and probe the
fuel pump relay connector terminal C or the EGI relay
connector terminal A. With the ignition switched On
the test lamp should light. If the test lamp does not light check the fuel pump
fuse and the wiring harness for continuity between the
ignition switch and the fuel pump relay connector
terminal C or EGI rela y connector terminal A.

(3) With the ignition remaining switched On,
connect the test lamp between the fuel pump relay
connector terminals C and B or the EGI relay
connector terminals A and B.

If the test lamp does not light, repair the open
circuit between terminal B and earth.

(4) When checking the EGI relay circuit, pro-
ceed to operation (9).

When checking the fuel pu mp relay circuit pro-
ceed as follows.

(5) Probe the relay connector terminal A with a
test lamp to earth. Switch the ignition On and note the
test lamp.

If the test lamp lights for 2 seconds, proceed to
step (7).

If the test lamp does not light as specified, proceed
as follows.

(6) Switch the ignition Off and backprobe the
control unit wiring connector terminal A1 with a test
lamp to earth. With the ignition switched On the test
lamp should light as previously described.

If the test lamp does not light as described, renew
the control unit.

If the test lamp does light as described, locate the
open circuit or short in the wiring harness between the
control unit wiring connector terminal Al and the
relay connector terminal A. Repair or renew the
wiring harness as necessary.

(7) With the ignition switched Off connect a
jumper lead between the relay connector terminals C
and D. (8) Switch the ignition On and listen for the
operation of the fuel pump. It should be possible to
feel vibrations in the fuel return hose. If the fuel pump is operating, the fuel pump relay
circuit can be considered serviceable.

If the fuel pump is not operating, check the wiring
harness for continuity between the fuel pump wiring
harness connector, the fuel pump relay connector
terminal D and earth. If no fault can be found, renew
the fuel pump.

(9) Probe the relay connector terminal C with a
test lamp to earth. The test lamp should light.

If the test lamp does not light, locate the open
circuit between the battery and terminal C. Check the
fusible link which is located third from the front in the
fusible link connecting block.

(10) Connect a jumper lead between the relay
connector terminals C and D and backprobe the
control unit wiring connector terminal A6 with a test
lamp to earth.

If the test lamp lights, the EGI relay circuit can be
considered serviceable.

If the test lamp does not light locate the open
circuit between the contro l unit wiring connector
terminal A6 and the relay connector terminal D.
Repair or renew the wiring harness as necessary.

COOLANT TEMPERATURE SENSOR
To Test — Codes 14 and 15
(1) Erase the self diagnosis code memory as
previously described. (2) Start and run the engine at idle speed for 60
seconds or until the ECM warning lamp lights.
(3) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connect or. Note any fault codes
displayed. If codes 14 or 15 are displayed, proceed to
operation (4).

If codes 14 or 15 are not displayed, but were
displayed when the self diagnosis test procedure was


View showing the location of the coolant temperature
sensor. 1.6 liter engine.

110 Fuel and Engine Management
originally performed, an intermittent fault is indi-
cated. Proceed as follows:

(a) Check for faulty wiri ng connections. Check
that all wiring connectors are clean and secure. (b) Check that all earth wires are secure.
(4) Disconnect the wiring connector from the
coolant temperature sensor. (5) With the ignition switched On, measure the
voltage across the terminals on the coolant tempera-
ture sensor wiring connector. The voltage should be
4-6 volts.
If the voltage is below 4 volts, proceed to opera-
tion (9).

If the voltage is as specified, proceed as follows.
(6) Remove the coolant temperature sensor
from the vehicle. (7) Connect an ohmmeter to the coolant temper-
ature sensor terminals. (8) Immerse the meta1 end of the coolant
tem-
perature sensor in a 50/50 mixture of glycol and iced
water at a temperature of 0 deg C. The resistance
should be 6 000 ohms. Slowly heat the mixture and measure the resis-
tance of the coolant temperature sensor at the follow-
ing temperatures. Compare the results with the spec-
ified values:

0 d e g C ................................................. 6 000 ohms
20 deg C .................................................. 2 500 ohms
30 deg C .................................................. 1 800 ohms
40 deg C.................................................. 1 200 ohms
70 deg C .......................................................450 ohms
90 degC .......................................................250 ohms
100 deg C.....................................................190 ohms
110 deg C.....................................................110 ohms
If the resistances obtained are not as specified at
any of the given temperatures, renew the coolant
temperature sensor and retest for fault codes.

(9) Disconnect the control unit wiring connec-
tors.
(10) Check the wiring harness for shorts and
continuity between the coolant temperature sensor
wiring connector terminals and the control unit wiring
connector terminals C10 and D2. Repair or renew the
wiring harness as necessary.
Also check the control unit terminals for damage.
If no fault is found, renew the control unit and
retest for fault codes.

To Remove and Install
(1) Disconnect the negative battery terminal.
(2) Disconnect the wiring connector from the
coolant temperature sensor.
(3) Drain the coolant as described in the Cooling
and Heating Systems section to a level below the
sensor.
(4) Unscrew the sensor from the thermostat
housing. Installation is a reversal of the removal procedure
with attention to the following points;

(1) Apply Loctite 675 or a similar conductive
sealer to the threads of th e sensor. Tighten the sensor
to the specified torque.
(2) Fill the cooling system with the correct
mixture of water and inhibitor as described in the
Cooling and Heating Systems section. (3) Ensure that the wiring connector is clean and
secure.
THROTTLE POSITION SENSOR
To Test - Codes 21 and 22

NOTE: The following test procedure as-
sumes that fault codes 21 or 22 have been
displayed during the se lf diagnosis test pro-
cedure. If no codes have been displayed but
the operation of the throttle position sensor
is suspect, begin the test procedure at oper-
ation (24).

(1) Erase the self diagnosis code memory as
previously described.
(2) Start and run the engine at idle speed for 60
seconds or until the ECM warning lamp lights. If the engine will not start, disconnect the throttle
position sensor wiring co nnector and proceed to
operation (8). .

(3) With the engine id ling, quickly increase the
engine speed to 3 000 rpm and return to idle.

If the ECM warning lamp remains illuminated,
proceed to operation (4).

If the ECM warning lamp extinguishes, an inter-
mittent fault is indicated. Proceed as follows:

(a) Check for faulty wiri ng connections. Check
that all wiring connectors are clean and secure. (b) Check that all earth wires are secure.
(4) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connect or. Note any fault codes
displayed.

If codes 21 or 22 are displayed, proceed as
follows.

(5) Remove the jumper lead from the diagnostic
link connector. (6) Erase the self diagnosis codes as previously
described. (7) Disconnect the wiring connector from the
throttle position sensor. If code 22 was displayed in operation (4), proceed
to operation (13).

If code 21 was displayed in operation (4), proceed
as follows.

(8) Start and run the engine at idle speed for 2
minutes or until the ECM warning lamp lights. If the
engine will not start, pr oceed to operation (11).
(9) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on

112 Fuel and Engine Management
If the voltage does not increase as specified, renew
the throttle position sensor.

If the voltage is as specified, proceed as follows.
(28) With the ignition switched On and the
throttle valve held fully open, measure the voltage at
control unit wiring connector terminal C13. The
voltage should be above 4 volts.

If the voltage is below 4 volts, renew the throttle
position sensor.

To Remove and Install
(1) Disconnect the negative battery terminal.
(2) On 1.6 liter engines, remove the air cleaner
assembly as previously described. (3) Disconnect the throttle position sensor wir-
ing connector. (4) Remove the throttle position sensor retain-
ing screws and remove the throttle position sensor
from the throttle body. Installation is a reversal of the removal procedure
with attention to the following points:

(1) Ensure that the throttle valve is in the fully
closed position. (2) Tighten the retaining screws securely and
install the wiring connector.

View of the throttle positi on sensor removed from the
throttle body assembly.
MANIFOLD AIR TEMPERATURE (MAT)
SENSOR - 1.8 LITRE ENGINE

To Test - Codes 23 and 25
(1) Erase the self diagnosis code memory as
previously described.
(2) Start and run the engine for 2 minutes or
until the ECM warning lamp lights. (3) Stop the engine, switch the ignition On and
connect a jumper lead between terminals A and B on
the diagnostic link connector . Note any fault codes
displayed. If codes 23 or 25 are displayed, proceed to
operation (4).

If codes 23 or 25 are not displayed but were
displayed when the self diagnosis test procedure was
originally performed, an intermittent fault is indi-
cated. Proceed as follows:

(a) Check for faulty wiri ng connections. Check
that all wiring connectors are clean and secure. (b) Check that all earth wires are secure.
(4) Disconnect the wiring connector from the
MAT sensor. (5) With the ignition switched On, measure the
voltage across the terminals on the MAT sensor wiring
connector. The voltage s hould be 4-6 volts.
If the voltage is below 4 volts, proceed to opera-
tion (9).

If the voltage is as specified, proceed as follows.
(6) Remove the MAT sensor from the engine.
(7) Connect an ohmmeter to the MAT sensor
terminals. (8) Immerse the metal end of the MAT sensor in
a container of iced water at a temperature of 4 deg C.
The resistance should be 7 500 ohms. Slowly heat the water and measure the resistance
of the MAT sensor at the following temperatures.
Compare the results with the specified values:

20 deg C .................................................. 3 400 ohms
38 deg C....................................................1 800 ohms
70 degC ...................................................... 450 ohms
100 deg C.................................................... 185 ohms
If the resistances obtained are not close to the
specified figures at any of the given temperatures,
renew the MAT sensor and retest for fault codes.

(9) Disconnect the control unit wiring connec-
tors. (10) Check the wiring harness between the MAT
sensor wiring connector and the control unit wiring
connector terminals C12 and A11 for shorts and
continuity. Also check the control unit terminals for
damage. Repair or renew the wiring harness as necessary.
If no fault is found, renew the control unit and
retest for fault codes.

To Remove and Install
(1) Disconnect the negative battery terminal.
Installed view of the MAT sensor. 1.8 liter engine.