1994 JAGUAR XJ low oil pressure

ZF Automatic Transmissions Service Manual
Valve
Reverse Gear
Clutches 'B','D' and 'E' are
engaged.
As the front planet gear carrier of epicyclic gear set
'1' is
locked, the direction of output shaft rotation is reversed.
Epicyclic gear set
'2' also rotates as a solid block.
Summary of function
J4L-698
Fig. 1
Pressure regulating
1-2 shift valve
2
-3 shift valve
1.1.4
This housing contains the output shaft and speed governor and the parking lock mechanism. The governor comprises
two spring loaded valves, a spindle and a weight; the governor is influenced by centrifugal and hydraulic forces and
supplies a varying hydraulic pressure.
The parking lock pawl operates on
a toothed wheel attached to the output shaft speed governor; the mechanism is
operated from the selector (position 'I") by actuator rod.
Transmission Output Shaft Extension Housing
Varies line pressure as required
Line pressure to
C & C1 clutch valves and dampers
Line pressure to
C1 clutch (2nd); line pressure to B clutch (3rd)
1.1.5 Transmission Control Unit
The hydraulic control unit comprising a series of valve blocks housing the manual (selector) valve, control pistons and
pressure valves, is attached to the underside of the transmission housing; the unit controls the operation of the gear
train clutches and directs oil pressure to the appropriate system components (refer to illustrations, pages 5 to 7 ) to
operate the transmission. The valve blocks are connected to a main gallery plate.
Line pressure from the hydraulic pump is supplied initially to the pressure regulating valve, manual valve, governor,
3
-4 shift valve, 'E' clutch and damper, throttle valve, modulator valve and torque converter pressure (and reversing)
valve. The function of each of the valves in the control unit and the governor valve is summarised in the table below.
2nd gear inhibit
3
-4 shift valve
Throttle valve
Modulator
Converter
& Reversing
Reverse inhibit
F Clutch inhibit
Converter clutch hysteresis
Converter clutch lock
-up
Converter clutch damper
Clutch valves
& Dampers
Governor Line pressure
to 2
-3 shift valve
Line pressure to
E clutch (3rd); line pressure to F clutch (4th)
Throttle pressure to modulator and shift valves
Modulated throttle pressure fed to clutch dampers and valves
Line pressure to lock
-up clutch; lubrication oil to cooler
Line pressure to B
& D clutches
Governor pressure to 3
-4 shift valve inhibited in reverse
Governor pressure to converter clutch hysteresis valve
Line pressure to converter pressure valve
(D4 selected)
Aids quality of converter clutch application
Aids quality of clutch application relevant to modulator
& line pressures
Varies pressure in accordance with road speed
Issue 1 August 1994 4

1.1.6 Gearshift Selection
Gearshift selection is by movement of the shift lever which through a selector cable causes repositioning ofthe manual
(selector) valve to direct oil pressure to the required shift valve. The automatic shift points are determined by acceler- ator position and road speed: throttle movement moves a cam on the throttle valve, directing oil pressure to the shift
valves and modulator valve, road speed modulates hydraulic pressure through a centrifugal governor driven by the
transmission output shaft. Operation
of the hydraulic control system is shown diagrammatically in the circuit dia
-
grams on the following pages.
I I
I
I
2 -3- I
I I
I
I
- I
I I 1 4 -5 - - -
+ ! + I I 'I 10 I I
I
I 1
1, 1-Y I
I I
I
I
1. Engine 8. Pump regulator valve 2. Torque converter 9. Damper
3. Pump 10. Governor valve 4. Clutch & gears 11. Shift valve 5. Governor 12. Kickdown cable &throttle cam 6. Shift 13. Throttle / modulator valves 7. Solenoid valve 14. Transmission housing
Fig.
1 Schematic Diagram of Hydraulic Control
I. 1.7 Throttle Valve Mechanism (kick-down)
The throttlevalve or 'kick-down' mechanism comprises a cable connected between throttle body pedal and the throttle
valve cam/ quadrant located on the selector valve shaft; the cam operates the throttle valve housed within the throttle
valve block. The travel of the valve is proportional to throttle positions and alters shift speeds and pressures during
gearshifts to take account of throttle position. The mechanism also provides for immediate selection of a lower
ratio (eg when overtaking) by depressing the accelerator beyond the normal full
-throttle position. 'Kick-down' is oper- ated by movement of the throttle cable into the 'kick-down' position causing full movement of the throttle valve and
directing oil flow to the shift valves.
1.1.8 Starter Inhibit Switch
The starter inhibit switch prevents the starter motor from being operated when the shift lever is not in position 'P' - Park or position 'N'- Neutral. The switch is located in the gear selector housing.
I. I. 9 Gearshift Interlock
A brake pedal /shift lever interlock is incorporated in the gearselector mechanism. Theshift lever may only be moved
from the 'P'- Park position if the ignition key switch is in position '11', and the foot brake pedal is applied. The ignition
key cannot be removed from the ignition switch unless the shift lever is in the 'P' -Park position. Once the ignition key
has been removed, the shift lever is locked in the park position.
The gearshift interlock is operated by an electrical solenoid located adjacent to the selector; an override latch is incorpo
- rated into the mechanism to enable the gearshift interlock to be manually overridden in the event of electrical failure
or when towing.
8 Issue 1 August 1994

ZF Automatic Transmissions Service Manual
a
2.3.6 Fault Finding Chart (continued)
Problem
Starter motor does not operate
'osition 'R' - Reverse
3everse gear inoperative
Slipping and juddering
Harsh
engagement'p-R' chan
'N-R' change (below 1500RPF
engine speed)
Reverse lamp does not
illuminate (bulbs, fuses and
cables functioning correctly)
Possible Cause
Rotary switch adjustment.
Rotary switch wiring fault.
Rotary switch faulty.
Position
'P or 'N' not selected.
vIV2 faulty.
rNire to MV2 earthed.
3il filter dirty.
Damper
'6' faulty.
Clutch
'6' faulty (also no 3rd gear).
Clutch 'D' faulty.
Clutch
'E' faulty (also no engine braking
in 2nd and 3rd gears).
Pressure regulator valve 1 binding
Rotary switch wiring fault.
Rotary switch faulty.
Reverse gear inhibit valve activated.
Main pressure control valve seized (also
no forward drive in 'D' Drive).
'B'Clutch, 'D'Clutch or 'E' Clutch faulty.
Pressure regulator valve 1 binding
'F'Clutch drum sealing rings faulty
causing
loss of 'E' Clutch pressure.
Damper
'6' faulty (also no 2nd to 3rd
shift).
Pressure regulator valve 1 binding
Modulation pressure too high.
Rotary switch faulty.
Rotary switch setting incorrect.
Rotary switch faulty.
Rotary switch wiring fault.
Action
4djust switch.
qectify.
3ectify or renew.
Select 'F" or 'N'.
Renew valve block.
Renew harness.
Clean
/ replace filter and flush out
the
oil cooler and pipes.
Renew valve block.
Renew transmission.
Renew transmission.
Renew transmission.
Renew valve block.
Rectify.
Rectify or renew.
Renew valve block.
Renew valve block.
Renew transmission.
Renew valve block.
Renew transmission.
Renew valve block.
Renew valve block.
Check TCM Fault Codes.
Rectify or renew.
Adjust setting.
Renew.
Rectify.
Issue 1 August 1994 62

ZF Automatic Transmissions Service Manual
Problem Possible Cause
2.3.6 Fault Finding Chart (continued)
e Action
Starter will not operate Rotary
switch faulty or incorrect setting. Rectify
or renew.
3rive not transmitted (neutral
:ondition)
Vehicle moves
Slipping and juddering at start Rotary
switch wiring fault. Rectify 'A'Clutch seized Renew
transmission
Checksecurity System
Harsh engagement
'N'-'D'(under 1500RPM engine
speed)
No 1st to 2nd upshift or 2nd to
1st downshift
No upshift 1st to 2nd
No upshift 2nd to 3rd or
downshift 3rd to 2nd
No upshift 2nd to 3rd
3il filter dirty.
Main pressure control valve seized.
Low oil level.
'A'Clutch faulty.
'D'Clutch one-way clutch slips. ~
'A'Clutch faulty
Low oil level.
'A'Clutch faulty.
'A'Clutch damper faulty (5).
Throttle pot. volts high.
Rotary switch faulty
/ out of adjustment.
MVI wire earthed(remains in 2nd gear).
MVI faulty.
Control circuit fault.
Shift valve
1-2 seized.
Pressure reducing valve
1 seized.
Speed sensor or connectors faulty.
Clutches
'Cl' and 'C' faulty
MV2 wire earthed (remains in 2nd gear).
MV2 faulty.
Shift valve 2
-3 seized.
Speed sensor faulty.
'B'Clutch faulty Clean
/ replace
filter.
Renew valve block.
Check oil level.
Renew transmission.
Renew transmission.
Renew transmission.
Check oil level.
Renew transmission.
Renew valve block.
Check throttle pot. volts.
Rectify or renew.
Renew harness.
Renew valve block.
Check TCM Diagnostics
/ rectify.
Renew valve block.
Renew valve block.
Check connections, rectify or
renew.
Renew transmission
Renew harness.
Renew valve block.
Renew valve block.
Rectify or renew.
Renew transmission
Issue 1 August 1994 63