check engine LAND ROVER DISCOVERY 1995 Manual Online

R380
1
FAULT DIAGNOSIS MANUAL GEARBOX
Symptom - Gear jumps out of engagement (any
forward gear)
1.Check condition and security of transmission
and engine mountings.
2.Check in situ, gear lever and selector
adjustments.
3.In situ, remove gearshift and check selector rail
yoke security.
Also check selector detent spring tension and
both spool retainers.
Suspect internal fault
See remove and overhaul procedure.
4.Check action/operation of main selector rail and
forks.
5.Check condition of synchromesh and gear dog
teeth.
6.Check main and layshaft end floats bearings and
adjustments.
7.Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Reverse gear only jumps out of
engagment
1.Check condition and security of transmission
and engine mountings.
2.Check in situ, gear lever and selector
adjustments.
3.In situ, remove gearshift and check selector rail
yoke security.
Also check selector detent spring tension and
both spool retainers.
Suspect internal fault
See remove and overhaul procedure.
4.Check action/operation of main selector rail and
reverse lever.
5.Check condition of reverse gear, angled
bearings and shaft.
6.Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.Symptom - Excessive force required to engage or
change gear, vehicle stationary or moving.
1.Check lubricant specification and level, if low do
not top up at this stage.
2.In situ, lubricate gear mechanism, and check
selector adjustments.
3.In situ, remove gearshift and check selector rail
is free and that the yoke is secure. Also check
selector detent spring tension and both spool
retainers.
4.Drain lubricant and check for contamination or
metal particles.
Suspect worn synchromesh unit or baulk rings
on affected gears. See remove and overhaul
procedure.
Symptom - Noisy gear engagement, vehicle
stationary.
See CLUTCH, Fault diagnosis, Clutch
Noise - Mechanical Faults
Symptom - Noisy gear selection, vehicle moving.
1.Confirm that clutch operation is satisfactory.
2.Establish which gear/gears is causing noise.
3.Check lubricant specification and level, if low do
not top up at this stage.
4.Drain lubricant and check for contamination or
metal particles.
Suspect worn synchromesh. See remove and
overhaul procedure.
5.Check condition of synchromesh unit, springs
and cones for distortion and wear. Also check
dog teeth for damage and cone mating surface
on gear for signs of overheating.
6.Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Noise from gearbox in neutral, which
changes tone or becomes worse when clutch is
depressed.
See CLUTCH, Fault diagnosis, Clutch
Noise - Mechanical Faults

R380
3
REPAIR Assembling transfer gearbox to main gearbox
45.Clean extension housing and transfer gearbox
mating faces.
46.Ensuring loose upper dowel is fitted, hoist
transfer gearbox into position.
47.Fit and tighten nut and bolts to
34Nm.
48.Connect high/low operating rod, fit and tighten
locknut.
49.Fit link to differential lock lever and secure with 2
clips
50.Align lever to high/low shaft, position washer, fit
bolt and new Nyloc nut. Tighten to
2Nm.
51.Position breather pipes, secure pipe unions
using new sealing washers. Tighten unions to
15Nm.
Fitting transfer gearbox and main gearbox
assembly to engine
52.Position transmission assembly to hoist cradle.
53.Clean bell housing and engine mating faces.
54.Temporarily fit gear lever and select any gear in
main gearbox to facilitate entry of gearbox input
shaft.
55.Position and raise hoist, and fit transmission to
engine whilst keeping wires and pipes clear to
prevent trapping.
56.Fit and tighten nuts securing transmission to
engine.
57.Connect reverse lamp switch connectors and
differential lock switch connectors.
58.Secure breather pipes to harness with clips.
59.Position temporary support.
60.Remove 2 bolts securing lifting cradle to
transmission and remove hoist. Apply Loctite
290 to bolts and refit bolts.
61.Position cross-member, loosely fit nuts and bolts
securing cross-member mountings to
transmission.62.Raise transmission, align cross-member and
loosely fit nuts and bolts securing cross-member
to chassis.
63.Tighten all securing nuts and bolts. Remove
supporting jack from under sump.
64.Remove temporary support.
65.Fit handbrake cable through transmission tunnel
and secure gaiter.
66.Connect speedometer cable to transfer gearbox.
67.Line up marks and connect front and rear
propeller shafts.
68.Clean spacer, clutch slave cylinder and gearbox
mating faces.
69.Position spacer and slave cylinder, fit bolts.
Tighten to
25Nm.
70.Untie intermediate exhaust pipe(s) and refit
exhaust front pipe(s).
See MANIFOLD AND
EXHAUST SYSTEM, Repair, Exhaust System
Complete
71.Refill main gearbox and transfer gearbox with oil.
See SECTION 10, Maintenance, Under
Vehicle Maintenance
72.Lower ramp [hoist].
73.Fit fan cowl, fit and tighten bolts.
74.Align breather pipe clip to cylinder block, fit and
tighten bolts.
75.Fit handbrake cable adjuster and secure with 'C'
clip.
76.Align cable trunnion to handbrake lever, fit clevis
pin and secure with clip.
77.Check handbrake adjustment.
See SECTION
10, Maintenance, Vehicle Interior
78.Fit upper gear lever, fit and tighten bolt.
79.Fit gear selector lever and high/low selector
lever draft excluders.
80.Position draft excluder clamp rings, fit and
tighten screws.
81.Refit sound insulation.
82.Refit centre console.
See CHASSIS AND
BODY, Repair, Centre Console
83.Connect battery earth lead.

41TRANSFER GEARBOX
2
FAULT DIAGNOSIS PROCEDURE
Prior to road test
1.Check oil level in transfer box is correct.
2.Check tightness of level and drain plugs.
3.Check breather system for blockage. To validate
the system the pipe must be removed,
inspected, rectified as necessary and refitted.
4.Remove all traces of oil from exterior of transfer
box.
Take vehicle for short road test.
5.Identify source of leaks and rectify as follows.
Front or rear output seal leaking:-
1.Drain the oil and remove the leaking output
flange.
2.Inspect the seal track on the flange for surface
damage. If damaged renew component.
3.Remove and discard the oil seal.
4.Inspect the seal locating bore and remove any
sharp edges which may damage the new oil
seal.
5.Fit new seal.
6.Fit the output flange and all the other parts.
7.Add oil to correct level into the gearbox.
See
LUBRICANTS, FLUIDS AND CAPACITIES,
Information, Recommended Lubricants and
Fluids
Cover plate gasket leaking.
1.Drain the oil and remove the leaking cover plate.
2.Remove all traces of joint sealant from both joint
faces.
3.Degrease all components and apply a thin film of
Hylomar sealant, to both joint faces.
4.Apply thread sealant to the bolts which come
into contact with gearbox oil.
5.Refit cover plate.
CAUTION: Care must be taken not to
overtighten the fixings.Leak between the main and transfer gearboxes.
1.Site vehicle onto a ramp [hoist].
2.Select neutral in transfer box and select 4th gear
in the main gearbox.
3.Run engine at 2000 rpm with the clutch/drive
engaged.
4.Observe joint between the main and transfer
boxes.
5.If oil leak is found establish if it is gear oil.
6.If so, the leak is originating from the transfer box.
7.Check the two inner (main/transfer) bolts are oil
tight, as these holes are tapped through into the
main transfer case.
8.Remove the transfer box to inspect the
mainshaft collar seal track condition, and the
front face of the transfer case for porosity.
See
Repair, LT230T Transfer Gearbox
9.If these areas require servicing, the transfer
gearbox input seal must also be renewed.
CAUTION: Avoid damaging the new seal
lip and ensure the seal is fitted flush with
the machined face. Also ensure the new
seal is not damaged when refitting the transfer
gearbox.
10.If red A.T.F type oil is seen leaking during the
workshop test, investigate the main gearbox for
cause of leak.
Detent plug or electrical switch leaks.
1.Detent plugs and electrical switches do not
usually leak. It must be noted that they fit into
open tapped holes in the transfer case and
therefore should be considered when looking for
the source of the leak.

41TRANSFER GEARBOX
2
REPAIR Remove
1.Site vehicle on a ramp [hoist].
2.Disconnect battery negative lead.
3.Remove fan cowl from radiator.
4.Remove transfer gear lever knob and gaiter.
5.Raise vehicle on ramp [hoist].
6.Drain oil and refit plug.
7.Detach heat shield at front exhaust pipe to
manifold.
8.Disconnect electrics to Lambda sensors.
9.Remove catalytic converter assembly.
10.Remove chassis crossmember from under
gearbox.
11.Remove heat shield from speedometer cable at
transfer gearbox.
12.Remove clamp and disconnect speedometer
cable from transfer gearbox. Tie cable to one
side.
13.Mark for reassembly then disconnect propeller
shaft to output flange, tie to one side.
14.Repeat on front propeller shaft to output flange.
15.Remove bolts retaining silencer front and rear
securing brackets and tie silencer to one side.
16.Place four 30mm long spacers between top of
hoist and adaptor plate, at securing points, and
secure adaptor plate to hoist.17.Remove four central bolts from transfer gearbox
bottom cover, move hoist into position and
secure adaptor plate to transfer gearbox.
18.Adjust hoist to take weight of transfer gearbox.
19.Remove tie bar, transfer gearbox to main
gearbox.
20.Remove nuts and bolts securing right transfer
gearbox mounting bracket to chassis.
21.Repeat for left mounting bracket. Removal of
these fixings will also free speedometer
transducer bracket.
22.Remove right side mounting bracket to flexible
mounting rubber.
23.Lower hoist until rear brake drum clears
passenger footwell. Check engine does not
crush any components while lowering.
24.Loosen park brake adjustment nut.
25.Remove park brake drum.
26.Remove park brake assembly complete from
rear output flange.
27.Disconnect leads from transfer gearbox
temperature sensor and differential lock warning
light switch.
28.Remove banjo bolt from breather pipe, retrieve
sealing washers and lay pipe aside.
29.Remove split [cotter] pin and washers securing
differential lock to connecting rod and disconnect
rod from lever.
30.Select low range transfer gearbox position.
31.Remove high/low rod lower lock nut and remove
rod from yoke.
32.Position hoist jack channel under bell housing.
33.Using wooden block support the main gearbox
and bell housing.
34.Remove upper and lower bolts securing transfer
gearbox to main gearbox.
35.Fit guide studs 18G 1425 to main gearbox and
move transfer gearbox rearwards to detach.

ZF
1
FAULT DIAGNOSIS ZF AUTOMATIC GEARBOX
Before referring to fault symptoms, carry out initial
static checks first:
INITIAL STATIC CHECKS
Check start positions 'P' & 'N' only........................................................
Reverse lights 'R' only..................................................................
Gear engagements N-D,N-3,N-2,N-1,N-R..........................................................
Full throttle Engine switched off, check full travel at engine and at.......................................................................
pedal.
Oil level 'N' selected, engine running at normal running............................................................................
temperature.
Pressure test
2000 rev/min 10±0.3 bar, 150±5 lbf/in
2....................................................................
Idle pressure 6.9±0.3 bar, 100±5 lbf/in2at 665 to 735 rev/min. ....................................................................
To fit pressure gauge
Service tools:
See Service tools, Automatic
Gearbox
0 to 20 bar, 0 to 300 lbf/in2Pressure gauge.
Flexible hose adaptor.
1.Site vehicle on a ramp [hoist].
2.From under gearbox, remove socket head plug
(located 10cm from oil pipe) Fit hose adaptor
LST502-1.
3.Fit hose to adaptor.
4.Fit gauge 18G502A to hose and route into
vehicle, ensuring hose is clear of rotating parts
and exhaust pipes.
5.Carry out road test.
See Road Test Procedure
Remove pressure gauge
6.Reverse removal procedure.

44AUTOMATIC GEARBOX
2
FAULT DIAGNOSIS ROAD TEST PROCEDURE
Follow the procedure given commencing each test,
from a standing start, on a level road, in good weather
conditions.
ROADTEST 1 = CHECKS 1-2-3-4-5-6-7-8
D SELECTED KICKDOWN START FROM REST
CHECK 1
Check for clutch squeal and slip. Check pressure is
150lbf/in
2
CHECK 2
Check 1st to 2nd upshift speed and quality. Pressure
should fall to 120 lbf/in
2.
CHECK 3
Check 2nd-3rd upshift speed and quality. Pressure
should fall to 100 lbf/in
2
CHECK 4
Release throttle to allow simultaneous engagement
4th + DDC. Check shift quality and engine rpm drop of
approximately 500 rpm.
CHECK 5
To proceed to Check 5 release throttle and check
drop out speed of direct drive clutch to 4th.
CHECK 6
Check down shift speed and quality 4th to 3rd.
NOTE: This shift is usually very smooth
and difficult to detect.
CHECK 7
Check downshift speed and quality 3rd to 2nd.
CHECK 8
Check downshift speed and quality 2nd to 1st. Also
difficult to detect.
END OF ROADTEST 1ROADTEST 2 CHECKS = 9-10-11
D SELECTED FROM REST
FULL THROTTLE START
CHECK 9
Check 1st-2nd upshift speed and quality.
CHECK 10
Check 2nd 3rd upshift speed and quality.
CHECK 11
Check 3rd 4th and direct drive clutch upshift speed
and quality.
NOTE: 4th and the direct drive clutch
engage simultaneously.
END OF ROADTEST 2

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

44AUTOMATIC GEARBOX
10
FAULT DIAGNOSIS FAULT SYMPTOMS
SYMPTOM 1 - Intermittent drive and high pitched
noise
FAULT - Low fluid level or restricted filter
SYMPTOM 2 - No drive in reverse
Select 'D'
ú No drive
FAULT - Continue with Symptom 3
ú Drives forward
FAULT - Reverse gear interlock valve
seized
Select '1'
ú No engine braking
FAULT - Clutch brake 3
SYMPTOM 3 - No drive from rest with 'D' selected
Select '1'
ú Vehicle drives
FAULT - No 2 freewheel
ú No drive
Carry out main line pressure check
ú Normal pressure
FAULT - Clutch A
ú No pressure
FAULT - Blocked filter or pump failure
ú Low pressure
FAULT - Restricted filter or sticking primary
regulator
SYMPTOM 4 - Slip in all forward gears
Carry out main line pressure check
ú No pressure
FAULT - Blocked filter or pump failure
ú Low pressure
FAULT - Restricted filter or sticking primary
regulator
ú Normal pressure
FAULT - Clutch 'A'SYMPTOM 5 - Harsh engagement 'N' to 'D'
Check engine idle speed
Carry out main line pressure check
ú High pressure
FAULT - Primary regulator stuck
ú Normal pressure
FAULT - Clutch 'A' or damper for clutch'A'
SYMPTOM 6 - Fierce shift or flare 1st to 2nd shift
Check engine idle speed
Carry out mainline pressure check
ú High pressure
FAULT - Continue with symptom 5
ú Normal pressure
FAULT - Modulator valve or dampers for
clutch brake CB1 and/or clutch brake CB2
FAULT - Clutch brake CB1 and/or clutch
brake CB2
SYMPTOM 7 - Fierce shift or flare 2nd to 3rd
Carry out mainline pressure check
ú High pressure
FAULT - Continue with symptom 5
ú Normal pressure
FAULT - Modulator valve or clutch 'B'
damper
FAULT - Clutch 'B'
SYMPTOM 8 - No 3rd gear
FAULT - 2-3 shift valve
FAULT - Clutch 'B'
SYMPTOM 9 - No 4th gear 'D' selected
FAULT - 4th to 3rd downshift valve stuck or
3rd to 4th upshift valve stuck
FAULT - Clutch brake 4

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