2005 MERCEDES-BENZ SPRINTER oil pressure

OUTPUT SHAFT SEAL
REMOVAL............................125
INSTALLATION........................125
PARK LOCK CABLE
REMOVAL............................125
INSTALLATION........................126
PISTONS
DESCRIPTION........................128
OPERATION..........................128
PLANETARY GEARTRAIN
DESCRIPTION........................130
OPERATION..........................130
DISASSEMBLY........................131
ASSEMBLY...........................131
SHIFT MECHANISM
DESCRIPTION........................133
OPERATION..........................133
REMOVAL............................134
INSTALLATION........................135
SOLENOID
DESCRIPTION........................136OPERATION..........................138
TEMPERATURE SENSOR/PARK-NEUTRAL
CONTACT
DESCRIPTION
DESCRIPTION - PARK/NEUTRAL CONTACT . 139
DESCRIPTION - TRANSMISSION
TEMPERATURE SENSOR..............140
OPERATION
OPERATION - PARK/NEUTRAL CONTACT . . 140
OPERATION - TRANSMISSION
TEMPERATURE SENSOR..............141
TORQUE CONVERTER
DESCRIPTION........................141
OPERATION..........................143
REMOVAL............................146
INSTALLATION........................146
TORQUE CONVERTER HUB SEAL
REMOVAL............................147
INSTALLATION........................147
AUTOMATIC TRANSMISSION -
NAG1
DESCRIPTION
The NAG1 automatic transmission (Fig. 1) is an
electronically controlled 5-speed transmission with a
lock-up clutch in the torque converter. The ratios for
the gear stages are obtained by 3 planetary gear sets.
Fifth gear is designed as an overdrive with a high-
speed ratio.
The gears are actuated electronically/hydraulically.
The gears are shifted by means of an appropriate
combination of three multi-disc holding clutches,
three multi-disc driving clutches, and two freewheel-
ing clutches.
Electronic transmission control enables precise
adaptation of pressures to the respective operating
conditions and to the engine output during the shift
phase which results in a significant improvement in
shift quality.
Furthermore, it offers the advantage of a flexible
adaptation to various vehicle and engines.
Basically, the automatic transmission with elec-
tronic control offers the following advantages:
²Reduces fuel consumption.
²Improved shift comfort.
²More favourable step-up through the five gears.
²Increased service life and reliability.
²Lower maintenance costs.
TRANSMISSION IDENTIFICATION
The transmission name, NAG1, means New Auto-
matic Gearbox, generation 1.
The transmission can be generically identified
visually by the presence of a round 13-way connector
located near the front corner of the transmission oil
pan, on the right side. Specific transmission informa-
tion can be found stamped into a pad on the left side
of the transmission, above the oil pan rail.
TRANSMISSION GEAR RATIOS
The gear ratios for the NAG1 automatic transmis-
sion are as follows:
1st Gear.............................3.59:1
2nd Gear............................2.19:1
3rd Gear............................1.41:1
4th Gear............................1.00:1
5th Gear............................0.83:1
Reverse.............................3.16:1
TRANSMISSION HOUSING
The converter housing and transmission are made
from a light alloy. These are bolted together and cen-
tered via the outer multi-disc carrier of multi-disc
holding clutch, B1. A coated intermediate plate pro-
vides the sealing. The oil pump and the outer multi-
disc carrier of the multi-disc holding clutch, B1, are
bolted to the converter housing. The stator shaft is
pressed into it and prevented from rotating by
splines. The electrohydraulic unit is bolted to the
transmission housing from underneath. A sheet
metal steel oil pan forms the closure.
21 - 2 AUTOMATIC TRANSMISSION - NAG1VA

MECHANICAL SECTION
The mechanical section consists of a drive shaft,
output shaft, a sun gear shaft, and three planetary
gear sets which are coupled to each other. The plan-
etary gear sets each have four planetary pinion
gears. The oil pressure for the torque converter
lock-up clutch and clutch K2 is supplied through
bores in the drive shaft. The oil pressure to clutch K3
is transmitted through the output shaft. The lubri-
cating oil is distributed through additional bores in
both shafts. All the bearing points of the gear sets, as
well as the freewheeling clutches and actuators, are
supplied with lubricating oil. The parking lock gear
is connected to the output shaft via splines.
Freewheeling clutches F1 and F2 are used to opti-
mize the shifts. The front freewheel, F1, is supported
on the extension of the stator shaft on the transmis-
sion side and, in the locking direction, connects the
sun gear of the front planetary gear set to the trans-
mission housing. In the locking direction, the rear
freewheeling clutch, F2, connects the sun gear of thecenter planetary gear set to the sun gear of the rear
planetary gear set.
ELECTROHYDRAULIC CONTROL UNIT
The electrohydraulic control unit comprises the
shift plate made from light alloy for the hydraulic
control and an electrical control unit. The electrical
control unit comprises of a supporting body made of
plastic, into which the electrical components are
assembled. The supporting body is mounted on the
shift plate and screwed to it.
Strip conductors inserted into the supporting body
make the connection between the electrical compo-
nents and a plug connector. The connection to the
wiring harness on the vehicle and the transmission
control module (TCM) is produced via this 13-pin
plug connector with a bayonet lock.
Fig. 1 NAG1 Automatic Transmission
1 - TORQUE CONVERTER 11 - PARKING LOCK GEAR
2 - OIL PUMP 12 - INTERMEDIATE SHAFT
3 - DRIVESHAFT 13 - FREEWHEEL F2
4 - MULTI-DISC HOLDING CLUTCH B1 14 - REAR PLANETARY GEAR SET
5 - DRIVING CLUTCH K1 15 - CENTER PLANETARY GEAR SET
6 - DRIVING CLUTCH K2 16 - ELECTROHYDRAULIC CONTROL UNIT
7 - MULTI-DISC HOLDING CLUTCH B3 17 - FRONT PLANETARY GEAR SET
8 - DRIVING CLUTCH K3 18 - FREEWHEEL F1
9 - MULTI-DISC HOLDING CLUTCH B2 19 - STATOR SHAFT
10 - OUTPUT SHAFT 20 - TORQUE CONVERTER LOCK-UP CLUTCH
VAAUTOMATIC TRANSMISSION - NAG1 21 - 3
AUTOMATIC TRANSMISSION - NAG1 (Continued)

SHIFT GROUPS
The hydraulic control components (including actua-
tors) which are responsible for the pressure distribu-
tion before, during, and after a gear change are
described as a shift group. Each shift group contains
a command valve, a holding pressure shift valve, a
shift pressure shift valve, overlap regulating valve,
and a solenoid.
The hydraulic system contains three shift groups:
1-2/4-5, 2-3, and 3-4. Each shift group can also be
described as being in one of two possible states. The
active shift group is described as being in the shift
phase when it is actively engaging/disengaging a
clutch combination. The 1-2/4-5 shift group control
the B1 and K1 clutches. The 2-3 shift group controls
the K2 and K3 clutches. The 3-4 shift group controls
the K3 and B2 clutches.
OPERATION
The transmission control is divided into the elec-
tronic and hydraulic transmission control functions.
While the electronic transmission control is responsi-
ble for gear selection and for matching the pressures
to the torque to be transmitted, the transmission's
power supply control occurs via hydraulic elements
in the electrohydraulic control module. The oil supply
to the hydraulic elements, such as the hydrodynamic
torque converter, the shift elements and the hydrau-
lic transmission control, is provided by way of an oil
pump connected with the torque converter.
The Transmission Control Module (TCM) allows for
the precise adaptation of pressures to the correspond-
ing operating conditions and to the engine output
during the gearshift phase, resulting in a noticeable
improvement in shift quality. The engine speed limit
can be reached in the individual gears at full throttle
and kickdown. The shift range can be changed in the
forward gears while driving, but the TCM employs adownshift safeguard to prevent over-revving the
engine. The system offers the additional advantage of
flexible adaptation to different vehicle and engine
variants.
EMERGENCY RUNNING FUNCTION
In order to ensure a safe driving state and to pre-
vent damage to the automatic transmission, the TCM
control module switches to limp-home mode in the
event of critical faults. A DTC assigned to the fault is
stored in memory. All solenoid and regulating valves
are thus de-energized.
The net effect is:
²The last engaged gear remains engaged.
²The modulating pressure and shift pressures
rise to the maximum levels.
²The torque converter lockup clutch is deacti-
vated.
In order to preserve the operability of the vehicle
to some extent, the hydraulic control can be used to
engage 2nd gear or reverse using the following pro-
cedure:
²Stop the vehicle.
²Switch off engine.
²Move selector lever to9P9.
²Wait at least 10 seconds.
²Start engine.
²Move selector lever to D: 2nd gear.
²Move selector lever to R: Reverse gear.
The limp-home function remains active until the
DTC is rectified or the stored DTC is erased with the
DRBttool. Sporadic faults can be reset via ignition
OFF/ON.
CLUTCH APPLICATION
Refer to CLUTCH APPLICATION for which shift
elements are applied in each gear position.
CLUTCH APPLICATION
GEAR RATIO B1 B2 B3 K1 K2 K3 F1 F2
1 3.59 X* X X* X X
2 2.19 X X X* X
3 1.41 X X X
4 1.00 X X X
5 0.83 X X X X*
NX X
R 3.16 X* X X X
* = The shift components required during coast.
21 - 4 AUTOMATIC TRANSMISSION - NAG1VA
AUTOMATIC TRANSMISSION - NAG1 (Continued)

DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - AUTOMATIC
TRANSMISSION
CAUTION: Before attempting any repair on a NAG1
automatic transmission, check for Diagnostic Trou-
ble Codes with the DRBTscan tool.
Transmission malfunctions may be caused by these
general conditions:
²Poor engine performance.
²Improper adjustments.
²Hydraulic malfunctions.
²Mechanical malfunctions.
²Electronic malfunctions.
²Transfer case performance.
Diagnosis of these problems should always begin
by checking the easily accessible variables: fluid level
and condition, gearshift cable adjustment. Then per-
form a road test to determine if the problem has been
corrected or if more diagnosis is necessary.
DIAGNOSIS AND TESTING - PRELIMINARY
Two basic procedures are required. One procedure
for vehicles that are drivable and an alternate proce-
dure for disabled vehicles (will not back up or move
forward).
VEHICLE IS DRIVABLE
(1) Check for transmission fault codes using DRBt
scan tool.
(2) Check fluid level and condition.
(3) Adjust gearshift cable if complaint was based
on delayed, erratic, or harsh shifts.
(4) Road test and note how transmission upshifts,
downshifts, and engages.
VEHICLE IS DISABLED
(1) Check fluid level and condition.(2) Check for broken or disconnected gearshift
cable.
(3) Check for cracked, leaking cooler lines, or loose
or missing pressure-port plugs.
(4) Raise and support vehicle on safety stands,
start engine, shift transmission into gear, and note
following:
(a) If propeller shaft turns but wheels do not,
problem is with differential or axle shafts.
(b) If propeller shaft does not turn and transmis-
sion is noisy, stop engine. Remove oil pan, and
check for debris. If pan is clear, remove transmis-
sion and check for damaged driveplate, converter,
oil pump, or input shaft.
(c) If propeller shaft does not turn and transmis-
sion is not noisy, perform hydraulic-pressure test to
determine if problem is hydraulic or mechanical.
DIAGNOSIS AND TESTING - ROAD TESTING
Before road testing, be sure the fluid level and con-
trol cable adjustments have been checked and
adjusted if necessary. Verify that all diagnostic trou-
ble codes have been resolved.
Observe engine performance during the road test.
A poorly tuned engine will not allow accurate analy-
sis of transmission operation.
Operate the transmission in all gear ranges. Check
for shift variations and engine flare which indicates
slippage. Note if shifts are harsh, spongy, delayed,
early, or if part throttle downshifts are sensitive.
Slippage indicated by engine flare, usually means
clutch, overrunning clutch, or line pressure problems.
A slipping clutch can often be determined by com-
paring which internal units are applied in the vari-
ous gear ranges. The Clutch Application chart
CLUTCH APPLICATION provides a basis for analyz-
ing road test results.
CLUTCH APPLICATION
GEAR RATIO B1 B2 B3 K1 K2 K3 F1 F2
1 3.59 X* X X* X X
2 2.19 X X X* X
3 1.41 X X X
4 1.00 X X X
5 0.83 X X X X*
NX X
R 3.16 X* X X X
* = The shift components required during coast.
VAAUTOMATIC TRANSMISSION - NAG1 21 - 23
AUTOMATIC TRANSMISSION - NAG1 (Continued)

DIAGNOSIS AND TESTING - AUTOMATIC TRANSMISSION
CONDITION POSSIBLE CAUSES CORRECTION
MAXIMUM SPEED 30 km/h 1. Speed Control 30 Actuated. 1. Instruct Customer.
ENGINE DIES WHEN
TRANSMISSION IS
SHIFTED INTO GEAR,
ALSO NOISES IN N
AND/OR P1. PWM Valve Blocked. 1. Replace Valve.
2. Torque Converter Lock Up Control
Valve Locked.2. Enable Movement of Valve,
Remove Particle.
LEVER IN9P9POSITION
BLOCKED (BRAKE
ACTIVATED)1. No Vacuum Brake Booster After
Long Immobilization, Brake Pedal
Not Fully Applied/Hard Pedal.1. Check Vacuum/ Tightness of
Brake Booster.
2. No Stoplamp Switch Signal (no
DTC IN ECM).2. Check Contact to Stoplamp
Switch. Replace Switch if
Necessary.
GRUMBLING, DRONING,
JERKING WHEN TCC IS
ENGAGED1. Slip Speed TCC to Low. 1. Switch Off Torque Converter
Lock Up Using DRBT.If
Complaint Is Not Reproduced
Afterwards, Replace PWM
Valve, Set Adaption Values to
Zero.
HOWLING, HUMMING
ABOVE 4000 RPM IN
EACH GEAR1. Oil Filter Blocked. 1. Replace Oil Filter.
2. Oil Pump. 2. Replace Oil Pump.
WHINING, SINGING 1. Gear Set Noises in 1st, 2nd, 5th
Gear.1. Replace Transmission..
2. Intermediate Bearing Of The Drive
Shaft At 0 km/h, Only When Cold.2. Replace Intermediate
Bearing of the Drive Shaft.
9CLACK9NOISE FROM
CENTER SHIFT AREA
WHEN STOPPING OR
STARTING1. Park Lock Solenoid. 1. Replace Shift Lever
Assembly.
CRACKING NOISE WHEN
LOAD CYCLE1. Stick - Slip Between Joint Flange
and Collar Nut.1. Install Zinc Coated Collar Nut
Together With Washer.
CHATTERING IN CENTER
CONSOLE SHIFT WHILE
ACCELERATING1. Bushing Shift Shaft Has Too Much
Clearance.1. Replace Shifter Lever and
Cover Plate.
HARD 2-3 UPSHIFT WHEN
STEPPING OFF THE
ACCELERATOR PEDAL1. Response Characteristic Control
Loop.1. Install K2 Disc Spring.
UPSHIFT 2-3, 3-4
SLIPPING1. Spring of Regulating Valve
Pressure control Valve Broken.1. Replace Spring.
HARD 2-1 DOWNSHIFT
WHEN COMING TO A
STOP1. Transmission (2-1 downshift) Not
Adapted.1. Re-adapt Transmission.
2. TCM Software Data. 2. Flash TCM.
3. Free Wheeling Clutch F1
Defective.Replace Free Wheeling Clutch
F1.
21 - 24 AUTOMATIC TRANSMISSION - NAG1VA
AUTOMATIC TRANSMISSION - NAG1 (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
DELAYED ENGAGEMENT,
NO TRANSFER OF
POWER IN R AND/OR D,
ALSO AT TIMES1. Oil Level Too Low. 1. Check Oil Level. Add if
Necessary.
2. Recognition Switch - Selector
Lever Position.2. Replace Recognition Switch
Only When Intermediate
Position or Fault is Indicated.
3. Oil Filter Not Installed. 3. Install Oil Filter.
4. AEV, Delayed Pressure Build Up
On Piston B2/B3.4. Install New Shifting
Procedure (TCM,
electrohydraulic control unit or
repair set).
5. Wrong Combination TCM/
Electrohydraulic Control Unit.5. Check Combination
TCM/Electrohydraulic Control
Unit. Replace TCM Resp.
Electrohydraulic Control Unit, if
necessary.
NO UPSHIFT OF 1ST
GEAR AT TIMES1. Connector Ballast Unit. Output
Speed Sensor Loose, Incorrectly
Contacted.1. Check Connectors, Replace
Output Speed sensor If
Necessary.
2. Output Speed Sensor Defective 2. Replace Output Speed
Sensor.
LEAKAGE AT THE AREA
OF THE ELECTRICAL
PLUG TO THE
CONDUCTOR PLATE1. Deformation O-Rings. 1. Replace O-Rings.
2. Deformation Adapter. 2.Replace Adaptor.
3. The Conductor Plate Is Not Fitted
Surface To Surface On The Valve
Body In One Corner, The Plug Is Not
Centered In The Socket And The
O-ring Will Not Seal.3. Remove Nose Of Conductor
Plate.
4. Contacting At The Conductor Plate
Leaky. Oil In Harness, Sometimes In
The Control Module.4. Replace Conductor Plate.
LEAKAGE AT THE AREA
OF BELL HOUSING/
TORQUE CONVERTER1. Bolts (Torx M6) Outer Disc Carrier
B1.1. Clean Thread and Install the
Bolts Using Sealer.
OIL LEAKS 1. 6 Lower Bolts (TorxM8) Converter
Housing.1. Clean Thread and Install the
Bolts Using Sealer.
2. Oil Drain Plug Converter Loose
Resp. No Seal Ring Installed.2. Install Drain Plug Correctly.
3. Weld Seam Of Torque Converter
Leaky.3. Replace Torque Converter.
4. Radial Sealing Ring Oil Pump
Defective.4. Replace Sealing Ring.
5. O-Ring Oil Pump Defective Or Not
Installed.5. Install O-Ring.
6. Bushing Of Oil Pump Loose,
caused By Missing Fit Bolt At
Transmission/Engine Flange.6. Install Fit Bolt If Necessary.
21 - 26 AUTOMATIC TRANSMISSION - NAG1VA
AUTOMATIC TRANSMISSION - NAG1 (Continued)

DRIVING CLUTCHES
DESCRIPTION
Three multi-plate driving clutches (Fig. 73), the
front, middle and rear multi-plate clutches K1, K2
and K3, are located in the planetary gear sets in the
transmission housing.
A multi-plate driving clutch consists of a number of
internally toothed discs (4) on an internally toothed
disc carrier and externally toothed discs (3) on an
externally toothed disc carrier.
OPERATION
The driving clutches (Fig. 74) produce a non-posi-
tive locking connection between two elements of a
planetary gear set or between one element from each
of two planetary gear sets in order to transmit the
drive torque.
If the piston (20) on multi-plate clutch K1 (1) is
subjected to oil pressure, it presses the internal and
external discs of the disc set together. The sun gear
(17) is locked with the planetary carrier (15) via the
externally toothed disc carrier (19) and the internally
toothed disc carrier (18). The front planetary gear set
is thus locked and turns as a closed unit.
Fig. 73 Driving Clutches
1 - K1 CLUTCH 12 - CENTER PLANETARY GEARSET SUN GEAR
2 - K2 CLUTCH 13 - K2 CLUTCH EXTERNALLY TOOTHED DISC CARRIER
3 - EXTERNALLY TOOTHED DISC 14 - K2 CLUTCH PISTON
4 - INTERNALLY TOOTHED DISC 15 - FRONT PLANETARY GEARSET PLANETARY CARRIER
5 - K3 CLUTCH 16 - FRONT PLANETARY GEARSET ANNULUS GEAR
6 - K3 CLUTCH EXTERNALLY TOOTHED DISC CARRIER 17 - FRONT PLANETARY GEARSET SUN GEAR
7 - K3 CLUTCH PISTON 18 - K1 CLUTCH INTERNALLY TOOTHED DISC CARRIER
8 - K3 CLUTCH INTERNALLY TOOTHED DISC CARRIER 19 - K1 CLUTCH EXTERNALLY TOOTHED DISC CARRIER
9 - REAR PLANETARY GEARSET SUN GEAR 20 - K1 CLUTCH PISTON
10 - CENTER PLANETARY GEARSET PLANETARY CARRIER 21 - DRIVE SHAFT
11 - CENTER PLANETARY GEARSET ANNULUS GEAR
21 - 72 AUTOMATIC TRANSMISSION - NAG1VA

(f) Adjust with snap-ring (8), if necessary. Snap-
rings are available in thicknesses of 2.0 mm (0.079
in.), 2.3 mm (0.091 in.), 2.6 mm (0.102 in.), 2.9 mm
(0.114 in.), 3.2 mm (0.126 in.), and 3.5 mm (0.138
in.).ELECTROHYDRAULIC UNIT
DESCRIPTION
The electrohydraulic control unit comprises the
shift plate made from light alloy for the hydraulic
control and an electrical control unit. The electrical
control unit comprises of a supporting body made of
plastic, into which the electrical components are
assembled. The supporting body is mounted on the
shift plate and screwed to it.
Strip conductors inserted into the supporting body
make the connection between the electrical compo-
nents and a plug connector. The connection to the
wiring harness on the vehicle and the transmission
control module (TCM) is produced via this 13-pin
plug connector with a bayonet lock.
ELECTRICAL CONTROL UNIT
The electric valve control unit (7) (Fig. 88) consists
of a plastic shell which houses the RPM sensors
(1,12), regulating solenoid valves (3, 4), solenoid
valves (5, 6, 10), the TCC solenoid valve (11), the
park/neutral contact (9), and the transmission oil
temperature sensor (8). Conductor tracks integrated
into the shell connect the electric components to a
plug connection (2). This 13-pin plug connection (2)
establishes the connection to the vehicle-side cable
harness and to the transmission control module
(TCM). With the exception of the solenoid valves, all
other electric components are fixed to the conductor
tracks.
HYDRAULIC CONTROL UNIT
Working Pressure (Operating Pressure) (p-A)
The working pressure provides the pressure supply
to the hydraulic control and the transmission shift
elements. It is the highest hydraulic pressure in the
entire hydraulic system. The working pressure is reg-
ulated at the working pressure regulating valve in
relation to the load and gear. All other pressures
required for the transmission control are derived
from the working pressure.
Lubrication Pressure (p-Sm)
At the working pressure regulating valve surplus
oil is diverted to the lubrication pressure regulating
valve, from where it is used in regulated amounts to
lubricate and cool the mechanical transmission com-
ponents and the torque converter. Furthermore, the
lubrication pressure (p-Sm) is also used to limit the
pressure in the torque converter.
Fig. 86 Measure K3 Clutch Clearance
1 - PRESSING TOOL 8901
2 - OUTER DISC CARRIER
Fig. 87 Driving Clutch K3 Stack-up
1 - OUTER DISC CARRIER
2 - OUTER MULTIPLE DISC - 4.0 MM (0.158 IN.)
3 - OUTER MULTIPLE DISC - 2.8 MM (0.110 IN.)
4 - OUTER MULTIPLE DISC - 1.8 MM (0.079 IN.)
5 - DISC SPRING
6 - PISTON
7 - FRICTION DISCS - 2.1 MM (0.083 IN.)
8 - SNAP-RING
21 - 82 AUTOMATIC TRANSMISSION - NAG1VA
DRIVING CLUTCH K3 (Continued)