check engine LAND ROVER DISCOVERY 1995 Workshop Manual

86ELECTRICAL
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DESCRIPTION AND OPERATION BUILT IN TEST PROCEDURE
The built in test procedure is accessed as follows:
1.Starting conditions: ignition off, doors unlocked,
bonnet [hood] switch depressed.
2.Carry out instructions 3 to 7 within 8 seconds.
3.Release bonnet [hood] switch.
4.Switch ignition ON.
5.Lock doors.
6.Switch ignition OFF.
7.Switch ignition ON.
If alarm is correctly accessed, horn will sound and
LED will flash. The following checks can be made:
8.Open and close any door or tailgate - LED will
light.
9.Depress bonnet [hood] switch - hazards will
flash.
10.Check engine cranking is disabled. Do not turn
off ignition.
11.Check ultrasonic by operating handset, LED will
emit one 5 second flash, and will flash if interior
is disturbed.
NOTE: If ECU is new born mode any
handset of the right frequency will work. If
not an initialised handset is required see
Handset Initialisation.
12.Turn OFF ignition or press handset to end test
procedure. Horn will sound as before to indicate
end of test mode.

ELECTRICAL
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FAULT DIAGNOSIS GENERAL INFORMATION
The electrical fault diagnostic tool on Discovery
vehicles is Testbook. Detailed information of electrical
systems, component locations and circuit diagrams
are covered in the Discovery Electrical
Troubleshooting Manual.
See INTRODUCTION,
Information, Fault Diagnostic Equipment
This section covers checks of the charging and
ignition system.
GENERATOR TESTING
Service repair no - 86.10.01
Charging system check
1.Check battery is in good condition, with an open
circuit voltage of at least 12.6 V. Recharge or
substitute battery to carry out test.
2.Check drive belt condition.
See SECTION 10,
Maintenance, Under Bonnet [Hood]
Maintenance
3.Check battery connections are clean and tight.
4.Check generator connections are clean and
tight.
5.Ensure there is no drain on battery from, for
example, interior, under bonnet [hood] or door
edge lamps.
Generator test
Following instructions refer to use of suitable test
equipment using a carbon pile rheostat.
6.Connect test equipment referring to
manufacturer's instructions.
7.Start engine and run at 3000 rev/min without
accessory load.
8.Rotate carbon pile load control to achieve
greatest output (amps) without allowing voltage
to fall below 12.0 V. A reading in amps, of
generator output, minus 10% to allow for EFI
and Ignition loss, should be obtained.
9.Run engine at 3000 rev/min, switch selector to
regulator test, read voltmeter. A reading of 13.6
to 14.4 V should be obtained.
10.Switch selector to diode/stator test, switch on
headlamps to load generator. Raise engine
speed to 3000 rev/min, read voltmeter, needle
must be within 'OK' range.TESTING IN POSITION
Charging circuit resistance test.
1.Connect a low range voltmeter between
generator terminal marked B+ and positive
terminal of battery.2.Switch on headlamps, start engine. Run engine
at approximately 3000 rev/min. Note voltmeter
reading.
3.Transfer voltmeter connections to frame of
generator and negative terminal of battery, and
again note voltmeter reading.
4.If reading exceeds 0.5 volt on positive side or
0.25 volt on negative side, there is a high
resistance in charging circuit which must be
traced and remedied.

86ELECTRICAL
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FAULT DIAGNOSIS LUCAS CONSTANT ENERGY IGNITION SYSTEM -
V8i
Preliminary checks
Inspect battery cables and connections to ensure they
are clean and tight. Check electrical condition of
battery.
Inspect all L.T. connections, ensure they are clean
and tight. Check H.T. leads are correctly positioned
and not shorting to ground against any engine
components. Wiring harness and individual cables
should be firmly fastened to prevent chaffing.
Pick-up air gap
Check air gap between pick-up limb and reluctor teeth
is 0.20 - 0.35 mm, using a non-ferrous gauge.
NOTE: Air gap is set initially at factory and
will only require adjusting if tampered with
or when pick-up module is replaced.
TEST 1:
H.T. Sparking
Remove coil/distributor H.T. lead from distributor
cover and hold approximately 6mm from engine block,
using suitable insulated pliers. Switch ignition 'On' and
operate starter.
Regular sparking indicates fault in H.T. distribution,
plugs, timing or fuelling, proceed to Test 6. If no spark
or weak spark occurs proceed to Test 2.TEST 2:
L.T. Voltage
Switch ignition 'On' - engine stationary.
(a) Connect voltmeter to points in circuit indicated
by V1 to V4 and make a note of voltage
readings.
(b) Compare voltages obtained with specified
values listed below:
Expected readings
V1 More than 12 volts.
V2 1 volt maximum below volts at V1.
V3 1 volt maximum below volts at V1.
V4 0 volt - 0.1 volt.
(c) If all readings are correct proceed to Test 3.
(d) Check incorrect reading(s) with chart to identify
area of possible faults, i.e. faults listed under
heading SUSPECT and rectify.
(e) If coil and amplifier is suspected, disconnect L.T.
lead at coil, repeat V3. If voltage is still incorrect,
fit new coil. If voltage is now correct, check L.T.
lead, if satisfactory fit new amplifier.
(f) If engine will not start proceed to Test 3.

86ELECTRICAL
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FAULT DIAGNOSIS TEST 4:
Pick-up Coil Resistance
Remove amplifier.
Connect ohmmeter leads to two pick-up terminals in
body of distributor.
The ohmmeter should register between 2k and 5k
ohm if pick-up is satisfactory. If ohmmeter reading is
correct, check all connections between pick-up and
amplifier, if satisfactory, fit new amplifier. If engine still
does not start carry out Test 5.
Change pick-up if ohmmeter reading is incorrect. If
engine still does not start proceed to Test 5.TEST 5:
Coil H.T. Sparking
Remove existing coil/distributor H.T. lead and fit test
H.T. lead to coil tower. Using suitable insulated pliers,
hold free end about 6mm from engine block and crank
engine. There should be good H.T. sparking.
If weak or no sparking, fit new coil, repeat test.
H.T. sparking good, repeat test with original H.T. lead.
If sparking is good carry out Test 6.
If weak or no sparking, fit new H.T. lead, if engine will
not start carry out Test 6.

ELECTRICAL
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FAULT DIAGNOSIS TEST 6:
Rotor Arm
Remove distributor cover. Disconnect coil H.T. lead
from cover, using insulated pliers hold about 3mm
above rotor arm electrode and crank the engine.
There should be no H.T. sparking between rotor and
H.T. lead. If satisfactory carry out Test 7.
If H.T. sparking occurs, an earth fault on rotor arm is
indicated. Fit new rotor arm. If engine will not start
carry out Test 7.
TEST 7:
Visual and H.T. Cable Checks
Examine: Should be:
1. Distributor Cover Clean, dry, no tracking marks.....................................................
2. Coil Top Clean, dry, no tracking marks....................................................................
3. H.T. Cable Insulation Must not be cracked, chafed or perished...............................................
4. H.T. Cable Continuity Must not be open circuit..............................................
5. Sparking Plugs Clean, dry, and set to correct gap........................................................
NOTE:
1. Reluctor Must not foul pick-up or leads...................................................................
2. Rotor and Insulation Cover Must not be cracked or show signs of tracking marks.....................................

ELECTRICAL
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ADJUSTMENT IGNITION TIMING
Service repair no - 86.35.15
Adjust
1.It is essential that following procedures are
adhered to. Inaccurate timing can lead to serious
engine damage and additionally create failure to
comply with emission regulations. If timing is
being checked in vehicle, air conditioning
compressor must be disengaged.
2.On initial engine build, or if distributor has been
disturbed for any reason, ignition timing must be
set statically to 6°B.T.D.C.
NOTE: This approximate setting is made
only to ensure that engine may be started.
CAUTION: On no account must engine be
started before this operation is carried out.Equipment required :-
Calibrated Tachometer
Stroboscopic lamp
3.Couple stroboscopic timing lamp and tachometer
to engine following manufacturer's instructions.
4.Disconnect vacuum hose from distributor.
5.Start engine. With no load, and without
exceeding 3,000 rev/min run engine until normal
operating temperature is reached. (Thermostat
open). Check that engine idles within tolerance
specified in data section.
6.Idle speed for timing purposes must not exceed
800 rev/min.
7.Run engine at idle speed and check timing using
stroboscope light on timing marker and pointer.
WARNING: Keep hands and equipment
away from belt.
8.If timing is not as specified, switch off engine.
Loosen distributor clamp bolt and turn distributor
to advance or retard ignition as necessary.
Tighten clamp bolt, start engine and recheck
timing.
WARNING: Personal injury may result if an
attempt is made to adjust distributor whilst
engine is running.
9.Upon completion, switch off engine and retighten
distributor clamping bolt securely. Recheck
timing, to ensure retightening has not disturbed
distributor position.
10.Refit vacuum hose.
11.Disconnect stroboscopic timing lamp and
tachometer from engine.

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REPAIR Refit
NOTE: If a new distributor is being fitted,
mark body in same relative position as
distributor removed.
8.Leads for distributor cap should be connected as
illustrated.
Figures 1 to 8 inclusive indicate plug lead
numbers.
RH-Right hand side of engine, when viewed
from rear.
LH-Left hand side of engine, when viewed from
rear.
9.If engine has not been turned while distributor
has been removed, carry out instructions 10. to
17. Alternatively proceed to instruction 18.
10.Fit new 'O' ring seal to distributor housing.
11.Turn distributor drive until centre line of rotor arm
is 30Ê anti-clockwise from mark made on top
edge of distributor body.
12.Fit distributor in accordance with alignment
markings.
NOTE: It may be necessary to align oil
pump drive shaft to enable distributor
drive shaft to engage in slot.
13.Fit clamp and bolt. Secure distributor in exact
original position.
14.Connect vacuum hose to distributor and low
tension lead to coil.
15.Fit distributor cap.
16.Reconnect battery.
17.Using suitable electronic equipment, set ignition
timing.
See Adjustment, Ignition timing
18.If engine has been turned with distributor
removed, carry out instructions 19 to 30.
19.Set engine-No. 1 piston to static ignition timing
figure
See ENGINE TUNING DATA,
Information, Engine 3.9 V8i
20.Turn distributor drive until rotor arm is
approximately 30Ê anti-clockwise from number
one sparking plug lead position on cap.
21.Fit distributor to engine.
22.Check that centre line of rotor arm is now in line
with number one sparking plug lead on cap.
Reposition distributor if necessary.
23.If distributor does not seat correctly in front
cover, oil pump drive is not engaged. Engage by
lightly pressing down distributor while turning
engine.
24.Fit clamp and bolt, do not tighten.
25.Set ignition timing statically to 6Ê B.T.D.C.
26.Connect vacuum hose to distributor.
27.Fit low tension lead to coil.
28.Fit distributor cap.
29.Reconnect battery.
30.Using suitable electronic equipment set the
ignition timing.
See Adjustment, Ignition
timing

86ELECTRICAL
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REPAIR PRINTED CIRCUIT AND WARNING LIGHTS
1. Panel illumination bulbs
2. Transmission oil temperature warning lamp bulb
3. Hazard warning lamp bulb
4. Check engine warning lamp bulb
5. Handbrake/brake fluid warning lamp bulb
6. ABS warning lamp bulb
7. Headlamp main beam warning lamp bulb
8. Trailer direction warning lamp bulb9. Direction indicator warning lamp bulb
10. Air suspension warning lamp bulb
11. Ignition/no charge warning lamp bulb
12. Seat belt warning lamp bulb
13. Not used
14. Traction control warning lamp bulb
15. Diesel heater plug warning lamp bulb (if fitted)
16. Main printed circuit

86ELECTRICAL
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OVERHAUL
LUBRICATION
Apply clean engine oil:
a. A spot into rotor spindle before fitting rotor
arm.
Apply Omnilube 2 (or equivalent) grease.
b. Auto advance mechanism.
c. Pick-up plate centre bearing.
d. Pre tilt spring and its rubbing area (pick-up
and base plate assembly).
e. Vacuum unit connecting peg (pick-up and
base plate assembly).
f. Connecting peg hole in vacuum unit
connecting rod.
Fitting pick-up and base plate assembly
1.Pick-up leads must be prevented from fouling
rotating reluctor. Both leads should be located in
plastic guide as illustrated. Check during
re-assembly.
Fitting reluctor
2.Slide reluctor as far as it will go on rotor shaft,
rotate reluctor until it engages with coupling ring
beneath pick-up base plate. Distributor shaft,
coupling ring and reluctor are 'keyed' and rotate
together. Fit 'O' ring, flat washer and retaining
circlip.Pick-up air gap adjustment
1.Air gap between pick-up limb and reluctor teeth
must be set within specified limits, using a
non-ferrous feeler gauge.
2.If adjustment is necessary, loosen two barrel
nuts to set the air gap.
See ENGINE TUNING
DATA, Information, Engine 3.9 V8i
NOTE: When original pick-up and base
plate assembly has been refitted, air gap
should be checked, and adjusted if
necessary.
When fitting a new assembly air gap will require
adjusting to within specified limits.
Amplifier module
1.Before fitting module, apply MS4 Silicone grease
or equivalent heat-conducting compound to
amplifier module backplate, seating face on
distributor body and both faces of heatsink
casting.