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ZF Automatic Transmissions Service Manual
1.3 FAULT DIAGNOSIS
The followina tables are intended as a auide to diaanosis of Dossible faults in the ZF 4 HP 22 transmission. When the
fault involvesa leak, it is recommendedthat it is located by the use of a crack detection fluid, eg Met-L-Check, which
is available in spray form and permits the leak to be located after a short test drive.
1.3.1 Initial Checks
Note: Before attempting diagnosis, ensure that the following settings are checked:
Transmission oil level.
. Ensure that the transmission is at normal operating temperature, eg by conducting a road test. If starting from cold,
. Check that the vehicle is on level ground.
. Firmly apply the parking and footbrakes and run the engine at idle speed.
. To ensure that the system is primed, slowly move the selector lever through all the gear positions.
. With the engine still running, engage ‘P‘ Park, withdraw the dipstick and wipe with a lint free cloth.
. Replace the dipstick slowly and withdraw it noting the level.
. Top up as required and recheck the level.
check
for presence of oil on dipstick at idle
in Park before start of road test.
1.3.2 Engine Tune
Selector cable adjustment.
Check gear selection in all selector positions.
If in doubt, select ’N’, disconnect the cable at the gearbox selector lever, check that the gearbox lever is in ’N’ position
. Adjust as necessary, see Vehicle Service Manual.
(third
detent from the rear) and refit the selector cable ball pin to the lever.
Kickdown switch adjustment, see Vehicle Service Manual.
1.3.3 Stall Test
. Ensure the transmission is at normal running temperature.
. Fully apply the parking brake.
. Fully depress the footbrake.
= Select position ‘D‘- Drive.
. Fully depress the accelerator(’kick-down’ detent fully depressed).
. Note the tachometer reading.
Start
the engine.
. Compare the tachometer reading to the specification.
CAUTION: This test must not last more than 5 seconds. Always allow the engine to idle for at least 2 minutes be- tween tests to allow the transmission fluid to cool down. Do not carry out more than three tests in any
half-hour.
1.3.4 Road Test
Fully check all shift speeds and note. Compare the results with the specification in addition to general observations
of transmission behaviour, noises, leaks etc., and consult the following Fault Finding Chart.
CAUTION: When renewing the transmission, ALWAYS flush out the oil cooler and feed and return pipes.
1.3.5 Electrical Checks
If any electrical component fault issuspected, referto the Electrical Diagnostic Manual (EDM) to verify the failure mode
before a repair or replacement is attempted.
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ZF Automatic Transmissions Service Manual
Problem Possible Cause
1.3.6 Fault Finding Chart
Action
Converter
Stall speed too low
Stall speed too
high and keeps
rising
Acceleration below specification
Top speed below specification
Position 'P'- Park
Will not move out of Park
Does not engage Park
Does not hold
Starter motor does not operate
Position 'R- Reverse
No reverse gear or severely
delayed engagement
High pitched squeaking noise Stator freewheel
faulty allowing
stator to revolve
Engine out of tune
Transmission slip.
Engine out of tune
Torque converter freewheel faulty
allowing stator to revolve.
Engine out of tune.
Torque converter freewheel seized.
Engine out of tune.
Gearshift interlock failure
Parking pawl mechanism sticking
Check cable adjustment
Parking pawl mechanism damaged
Check cable adjustment
Starter
inhibit switch faulty.
Faulty selector lever.
Position
'P' or 'N' not selected.
Check cable adjustment
Dirty oil filter.
Jammed governor.
Jammed reverse inhibit valve.
Low oil level.
'B' clutch destroyed (also no 3rd
gear
in Drive).
'D' clutch destroyed.
'E' clutch destroyed (no engine
braking
in 2nd & 3rd gears.
Reverse gear safety valve faulty. Renew
torque converter
Check engine tune.
Check oil level, check mechanical
failure, renew transmission as
necessary.
Renew torque converter.
Check engine tune.
Renew torque converter.
Check engine tune.
Rectify. Renew fuse, check circuits,
renew relay and solenoid.
Renew park pawl components:
connecting bar, pawl
pin, tension
spring, guide piece
& guide sheet
Adjust cable as necessary.
Replace park pawl components
Adjust cable as necessary.
Replace switch.
Replace lever.
Select 'P'
or 'N'.
Adjust cable as necessary.
Renew oil filter.
Replace governor.
Replace valve block.
Check oil.
Service
/ renew transmission.
Service
/ renew transmission.
Service
/ renew transmission.
Service
/ renew valve block.
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1.3.6 Fault Finding Chart (continued)
Problem Possible Cause
slipping or shaking from start in
'everse gear
Strong jerk, or distant double
erk, when engaging positions
P
-R', or 'N-R' (below 1500RPM
tngine speed)
'B','E or 'D' clutch defective
Damper
'6' defective (will give the
same symptoms when changing
from 2nd to 3rd gears
Action
Service 1 renew transmission.
Service
1 renew valve block
qeverse lamp does not illuminate Starter inhibit switch faulty.
bulbs, fuses and cables
'unctioning correctly) Faulty selector lever.
io drive or severe delay. Renew
switch.
Renew lever.
Slipping or shaking during initial Position
'R' not
selected.
'orward movement
Strong jerk 'N
-D' (below 1500
3PM engine speed) Select
'R'.
Sear change functions
faulty (in c'
Zhange 1st to 2nd 12nd to 1st Governor dirty.
Shift valve 1-2 sticking.
Zhange 1st to
2nd
Renew governor.
Renew valve block.
Zhange 2nd to 3rd
13rd to 2nd
Governor dirty.
Shift valve 3
-4 sticking.
:hange 2nd to 3rd
Zhange 3rd to
4th I 4th to 3rd Renew
governor.
Renew valve block.
Sudden shifts
Jehicle starts in 2nd gear Governor sleeve sticking.
Shift valve 1
-2 sticking.
Governor sleeve sticking.
Shift valves 1
-2 and 2-3 sticking.
Jehicle starts in 3rd gear Renew
governor.
Renew valve block.
Renew governor.
Service
I renew valve block.
Searbox changes 1st to 3rd
Uo shifts Dirty
oil filter.
Oil level incorrect.
'A' clutch defective.
'D' clutch one
-way clutch faulty.
'A' clutch damaged
'A' clutch faulty.
'A' clutch damper faulty.
Id or warm state)
If there is no debris in sump, renew the
oil filter and oil;
if debris is present in
the sump, renew the transmission.
Check oil level.
Service
I renew transmission.
Service
1 renew transmission.
Service
I renew transmision
Service
1 renew transmission.
Service
/ renew valve block.
Brake
'Cl' and 1 or 'C' faulty I Service / renew transmission
Governor dirty.
I Renew governor.
Shift valve 2-3 sticking.
'B' clutch faultv
Renew valve block.
Service
I renew transmission
Dampers sticking
I Service I renew valve block
Shift valve 2
-3 sticking I Service 1 renew valve block
Governor sticking.
Dampers sticking. Change
governor.
Service
I renew valve block
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