Range Rover Classic. Manual — part 72
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 æ 0.3 bar, 150 æ 5 lbf/in
2
. . . . . . . . . . . . . . . . .
Idle pressure
6.9 æ 0.3 bar, 100 æ 5 lbf/in
2
at 665 to 735 rev/min.
. . . . . . . . . . . . . . . . .
To fit pressure gauge
Service tools:
See Service tools, Automatic
Gearbox
0 to 20 bar, 0 to 300 lbf/in
2
Pressure 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.
44
AUTOMATIC 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 10
bar, 150lbf/in
2
CHECK 2
Check 1st to 2nd upshift speed and quality. Pressure
should fall to 8.2 bar, 120 lbf/in
2
.
CHECK 3
Check 2nd-3rd upshift speed and quality. Pressure
should fall to 6.8 bar, 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 1
ROADTEST 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
44
AUTOMATIC GEARBOX
4
FAULT DIAGNOSIS
AUTOMATIC GEARBOX ASSEMBLY ILLUSTRATED
1. Gearbox assembly
2. Inhibitor switch assembly
3. Control unit assembly
4. Filter and sump assembly
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