check engine light LAND ROVER DISCOVERY 1995 User Guide

ZF
3
FAULT DIAGNOSIS ROADTEST 3 = CHECKS
12-13-14-15-16-17-18-19-20-21-22-23
D SELECTED FROM REST
LIGHT THROTTLE START
CHECK 12
Check 1st 2nd upshift speed and quality.
CHECK 13
Check 2nd 3rd upshift speed and quality.
CHECK 14
Check 3rd 4th upshift speed and quality.
NOTE: This shift is usually very difficult to
detect but can be confirmed by a 200 rpm
drop in engine speed.
CHECK 15
Check speed and quality of shift into direct drive
clutch, confirmed by 300 rpm drop in engine speed.
NOTE: An intermediate throttle position
engagement of 4th and the direct drive
clutch, which is indicated by a fall of
500rpm in engine speed.
CHECK 16
At approximately 88 kph (55 mph) depress throttle to
kickdown - gearbox should change down to 2nd -
release throttle to re-engage 4th direct drive clutch
continue to accelerate gently.
CHECK 17
At approximately 128 kph (80 mph) depress throttle to
kickdown - gearbox should change down to 3rd -
release throttle to re-engage 4th direct drive clutch
and continue to accelerate gently.CHECK 18
At approximately 138 kph (85 mph) select 3rd,
gearbox should change immediately down to 3rd.
Release throttle.
CHECK 19
De-accelerate to approximately 47 kph (30 mph)
depress throttle to kickdown - geabox should
downshift to 1st gear, continue accelerating at full
throttle until 3rd gear is attained. To do this you will
have repeated check 2 of Test 1.
CHECK 20
At 128 kph (80 mph) select 2nd no downshift should
occur. Release throttle.
CHECK 21
At 104 kph (65 mph) an automatic downshift into 2nd
gear should occur. Continue to de-accelerate.
CHECK 22
At 88 kph (55 mph) select 1st. No downshift should
occur. Continue to de-accelerate.
CHECK 23
With 1 selected 2nd gear engaged continue to
de-accelerate and at 45 kph (28 mph) the box should
automatically downshift to 1st gear after which no
upshifts will occur in this selector position.
END OF ROADTEST

ZF
11
FAULT DIAGNOSIS SYMPTOM 10 - None or harsh engagement of
direct drive clutch
NOTE: The direct drive clutch will only
engage if 4th gear is engaged at 40 to 45
mph.
Carry out road test pressure check with gauge
connected to torque converter.
ú Normal pressure
FAULT - Failed direct drive clutch
ú Pressures correct but remains high
FAULTS POSSIBLE -
Direct drive clutch and torque converter
control valve stuck
Hysteresis valve stuck
Direct drive clutch control valve stuck
SYMPTOM 11 - Direct drive clutch shift point
incorrect or at low speed
NOTE: Direct drive clutch engagement at
low speed will cause vibration in the
torque converter
Carry out mainline and torque converter pressure
check
ú Normal pressure
FAULT - Governor valve sticking
ú Low or incorrect pressure
FAULTS POSSIBLE -
Direct drive clutch and torque converter
control valve sticking.
Hysteresis valve stuck.
Direct drive clutch control valve stuck.
SYMPTOM 12 - Drives in 'D' but immediately
upshifts to 3rd
FAULT - 2nd to 3rd shift valve stuck.
SYMPTOM 13 - With 'D' selected vehicle starts in
2nd
FAULTS POSSIBLE -
1st and 2nd shift valve stuck.
Governor sleeve sticking.
SYMPTOM 14 - With 'D' selected vehicle starts in
3rd
FAULTS POSSIBLE -
1st to 2nd and 2nd to 3rd shift valves stuck.
Governor sleeve sticking.SYMPTOM 15 - No kickdown 4th to 3rd
FAULT - 4th to 3rd kickdown valve stuck.
SYMPTOM 16 - Upshifts/downshifts and kickdown
shifts at incorrect road speeds
Check throttle kickdown cable adjustment
Carry out main line pressure check
ú Normal pressure
FAULT - Governor valve sticking
ú Incorrect pressure
FAULTS POSSIBLE -
Incorrect throttle valve adjustment
Primary regulator sticking
SYMPTOM 17 - No upshifts at light throttle
FAULTS POSSIBLE
Governor valve sticking
Shift valves sticking
SYMPTOM 18 - No engine braking '3' selected 3rd
gear
FAULT - Clutch 'C'
SYMPTOM 19 - Delayed or no downshift occurs
when making a manual selection from '3' to '2'
FAULTS POSSIBLE -
2nd and 3rd upshift valve sticking.
Governor valve sticking.
'2' Position interlock valve sticking.
SYMPTOM 20 - At speeds below 28 mph when
making a manual selection from '2' to '1',
downshift is delayed or does not occur
FAULTS POSSIBLE -
Governor sticking.
1st to 2nd shift valve sticking.
'1' Position interlock valve sticking.
SYMPTOM 21 - '1' Selected 1st gear no engine
braking
FAULT - Clutch brake 3
SYMPTOM 22 - '2' Selected 2nd gear no engine
braking
FAULT - Clutch brake 1
SYMPTOM 23 - Vehicle drives forward in 'N'
FAULT - Clutch 'A' stuck

ZF
3
REPAIR 19.Disconnect rear propeller shaft to output flange,
and tie to one side.
20.Repeat instructions 18 and 19 on front propeller
shaft to main gearbox.
21.Remove bolts retaining silencer front and rear
securing brackets and tie silencer to one side.
22.Disconnect oil cooler feed and return pipes from
bottom and side of main gearbox.
23.Release cooler pipes from clamp at engine sump
and remove distance piece.
24.Blank pipe ends and unions.
25.Move oil cooler pipes clear of transmission and
tie aside.
26.Disconnect selector cable from operating lever.
27.Disconnect inhibitor switch at multiplug.
28.Attach adaptor plate to hoist.
29.Remove two bolts from transfer gearbox rear
cover.
30.Raise hoist to align adaptor plate with transfer
gearbox and transmission. Secure to transfer
gearbox at rear cover with two bolts removed.
31.Adjust hoist to take weight of transmission.
32.Remove nuts and bolts securing right transfer
gearbox mounting bracket to chassis.
33.Repeat for the left mounting bracket. Removal of
these fixings will also free speedometer
transducer bracket
34.Remove right side mounting bracket to flexible
mounting rubber retaining nut.
35.Lower hoist until rear brake drum clears
passenger footwell. Check engine does not
crush any components while lowering.
36.Remove clip and clevis pin from park brake
lever.
37.Remove clip securing outer brake cable
38.The park brake cable is now free.
39.Disconnect leads from transfer gearbox
temperature sensor and differential lock warning
light switch.
40.Remove ties securing breather pipes to harness.
41.Remove bell housing access plate complete with
gasket.
42.Rotate engine, using crankshaft pulley, until two
access holes are visible in drive plate/ring gear
assembly through bell housing bottom cover
opening.
43.Identify an access hole and bolt hole to aid
reassembly.
44.Remove bolts securing drive plate to convertor
through access holes.
45.Rotate crankshaft half turn to access and
remove remaining bolts.
46.Disconnect oil dipstick tube at main gearbox.
47.Remove bolt at bell housing and detach dipstick
tube. Blank pipe end and union.
48.Position hoist jack channel under engine and
support using a wooden block.
49.Remove bell housing to engine securing bolts,
also detach harness bracket from bell housing.
50.Ease transmission rearwards to allow access to
secure torque converter in bell housing.
51.Lower hoist and complete removal of
transmission.
Refit
52.Ensure torque converter is retained in bell
housing.
53.Secure transmission to adaptor plate on lifting
hoist.
54.Raise hoist and locate transmission with engine.
55.Remove torque converter retainer.
56.Complete attachment of transmission to engine
and fit bell housing bolts. Fit the dipstick tube
bracket and harness bracket to their respective
bolts.
57.Complete refitting by reversing removal
procedure. Note the following important points.
58.Drive plate to torque converter bolts are to be
coated with Loctite 290 prior to assembly.
59.Refill transfer and main gearboxes with correct
grade oil.
See LUBRICANTS, FLUIDS AND
CAPACITIES, Information, Recommended
Lubricants and Fluids
60.Check operation of parking brake and adjust as
necessary.
See SECTION 10, Maintenance,
Vehicle Interior

BRAKES
1
FAULT DIAGNOSIS ABS FAULT DIAGNOSIS
If a fault has occurred, or has been identified by ECU
self diagnostic function and ABS warning light is
illuminated. The system and components must be
checked to locate and rectify fault, using Testbook
diagnostics.
NOTE: If warning lamp has indicated a
fault in system, and no fault code has been
stored in memory, cause of fault is:
a) Failure in electrical supply
b) Bad ECU ground
c) Faulty warning light relay
d) ECU not connected
Before commencing fault diagnosis procedure
following items must be checked:
1.Inspect all exposed cables for damage or
abrasion.
2.Check ground on ABS system.
3.Battery - state of charge.
4.Check hub end-float.
5.All ABS fuses and electrical connections.
Fault rectification
1.Complete harness should be replaced if faults
are found in wiring harness.
2.DO NOT use unspecified cables or connectors,
as this could jeopardise safe function of ABS.
3.DO NOT attempt to open sealed 35 way
connector to ECU.FAULT DIAGNOSIS PROCEDURE
NOTE: If ABS warning light illuminates due
to large sensor air gap, fault will be
retained by the ECU memory. Where wheel
sensors have been pushed fully home prior to
test, The ECU will indicate a fault that has been
rectified.
NOTE: After any steering adjustment,
bearing replacement/adjustment, brake
disc replacement: Check hub end-float and
sensor clearance.
RELAYS AND FUSES ABS
The location and identification of ABS electrical relays
are given in the Electrical Troubleshooting Manual
For location and identification of ABS electrical fuses.
See ELECTRICAL, Repair, Fuse Box - Interioror.
See ELECTRICAL, Repair, Fuse Box - Engine
Compartment

ELECTRICAL
1
DESCRIPTION AND OPERATION ELECTRICAL EQUIPMENT
DESCRIPTION
The electrical system is Negative ground, and it is
most important to ensure correct polarity of the
electrical connections at all times. Any incorrect
connections made when reconnecting cables may
cause irreparable damage to the semi-conductor
devices used in the generator and regulator. Incorrect
polarity would also seriously damage any
transistorized equipment such as radio and
tachometer etc.
WARNING: During battery removal or
before carrying out any repairs or
maintenance to electrical components
always disconnect the battery negative lead first.
If the positive lead is disconnected with the
negative lead in place, accidental contact of the
wrench to any grounded metal part could cause a
severe spark, possibly resulting in personal
injury. Upon installation of the battery the positive
lead should be connected first.
GENERATOR
The generator is a three phase, field sensed unit. The
rotor and stator windings produce three phase
alternating current, AC, which is rectified to direct
current, DC. The electronic voltage regulator unit
controls the generator output voltage by high
frequency switching of the rotor field circuit. Use only
the correct Vehicle replacement fan belt. Occasionally
check that the engine and generator pulleys are
accurately aligned.
It is essential that good electrical connections are
maintained at all times. Of particular importance are
those in the charging circuit (including those at the
battery) which should be occasionally inspected to
see that they are clean and tight. In this way any
significant increase in circuit resistance can be
prevented.Do not disconnect battery cables while the engine is
running or damage to the semi-conductor devices
may occur. It is also inadvisable to break or make any
connections in the generator charging and control
circuits while the engine is running.
The electronic voltage regulator employs micro-circuit
techniques resulting in improved performance under
difficult service conditions. The whole assembly is
encapsulated in silicone rubber and housed in an
aluminium heat sink, ensuring complete protection
against the adverse effects of temperature, dust, and
moisture etc.
The regulating voltage is set during manufacture to
give the required regulating voltage range of 14.2±
0.2 volts, and no adjustment is necessary. The only
maintenance needed is the occasional check on
terminal connections and wiping with a clean dry
cloth.
The generator system provides for direct connection
of a charge (ignition) indicator warning light, and
eliminates the need for a field switching relay or
warning light control unit. As the warning lamp is
connected in the charging circuit, lamp failure will
cause loss of charge. Lamp should be checked
regularly and spare carried.
When using rapid charge equipment to re-charge the
battery, the battery must be disconnected from the
vehicle.
NOTE: For description and operation of
electrical circuits see separate publication:
Electrical Troubleshooting Manual.

86ELECTRICAL
4
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
1
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.

86ELECTRICAL
6
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
34
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