clutch MERCEDES-BENZ SPRINTER 2006 Service Manual

1.0 INTRODUCTION
The procedures contained in this manual include
all of the specifications, instructions, and graphics
needed to diagnose NAG1 Electronic Automatic
Transmission and Shift Lever Assembly problems.
The diagnostics in this manual are based on the
failure condition or symptom being present at the
time of diagnosis.
When repairs are required, refer to the appropri-
ate volume of the service information for the proper
removal and repair procedure.
READ THIS MANUAL BEFORE TRYING TO
DIAGNOSE A VEHICLE TROUBLE CODE.
Diagnostic procedures change every year. New
diagnostic systems may be added and/or carryover
systems may be enhanced. It is recommended that
you review the entire manual to become familiar
with all new and changed diagnostic procedures.
1.1 SYSTEM COVERAGE
This diagnostic procedures manual covers all
Sprinter (VA) equipped with a NAG1 Automatic
Transmission.
1.2 SIX -STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the NAG1 electronic transmission is
done in six basic steps:
Verification of complaint
Verification of any related symptoms
Symptom analysis
Problem isolation
Repair of isolated problem
Verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
The NAG1 Transmission family can be identified
by the presence of a 13 pin electrical connector, with
a bayonet lock on the right hand side of the trans-
mission. The connector is oriented horizontally.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 GENERAL DESCRIPTION
The NAG1 electronic transmission is an electron-
ically controlled five speed transmission with a
controlled slip torque converter. The NAG1 elec-tronic transmission is a conventional transmission
in that it uses hydraulically applied clutches to shift
a planetary gear train. However, the electronic
control system replaces many of the mechanical and
hydraulic components used in conventional trans-
mission valve bodies.
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 electronic
control system enables precise adaptation of pres-
sures to the respective operating conditions and to
the engine output during a shift phase, which
results in a significant improvement in shift qual-
ity.
3.2 FUNCTIONAL OPERATION
The NAG1 electronic transmission has a fully
adaptive control system. The system performs its
functions based on continuous real-time sensor and
switch feedback information. In addition the TCM
receives information from the Shift Lever Assembly,
ECM (engine management) and ABS (chassis sys-
tems) controllers over the CAN bus. The CAN bus is
a high speed communication bus that allows real
time control capability between various controllers.
Most messages are sent every 20 milliseconds, this
means critical information can be shared between
the Transmission, Shifter, Engine and ABS control-
lers. The CAN bus is a two wire bus with aCAN C
Bus (+) circuitand aCAN C Bus (-) circuit. The
CAN bus uses a twisted pair of wires in the harness
to reduce the potential of radio and noise interfer-
ence. The CAN bus also uses a 120 ohm terminating
resistor in both the ECM and Sentry Key Remote
Entry Module (SKREEM) modules. The module
terminating resistance is measured across both
CAN bus circuits at the ECM or SKREEM module.
The control system automatically adapts to
changes in engine performance, vehicle speed, and
transmission temperature variations to provide
consistent shift quality. The control system ensures
that clutch operation during upshifting and down-
shifting is more responsive without increased
harshness. The TCM controls the actuation of sole-
noid valves for modulating shift pressure and gear
change. The required pressure level is calculated
from the load condition, engine speed. Power for the
transmission system is supplied through the Trans-
mission Relay. The TCM is located in the under the
drivers seat of the vehicle.
The Transmission Control Module (TCM) contin-
uously checks for electrical problems, mechanical
problems, and some hydraulic problems. When a
problem is sensed, the TCM stores a diagnostic
trouble code (DTC). Some of these codes cause the
transmission to go into9limp-in9or9default9mode.
1
GENERAL INFORMATION

3-4 solenoid -The 3-4 solenoid is activated when
the TCM determines that the transmission must
shift into or out of 4th gear. The solenoid is only
activated during the shifting of the transmission.
When the solenoid is activated, hydraulic pressure
is applied to the proper shift elements in the trans-
mission to allow the desired shift. Once the shift is
completed, the solenoid is turned off.
TCC solenoid -The TCC solenoid is activated
when the TCM determines that the Torque con-
verter clutch should be activated. The TCC clutch is
a variable slip torque clutch that allows control of
torque converter slip from 5% to 95.5% of full TCC
engagement. The clutch is controlled by the TCC
solenoid which is pulse width modulated (PWM) to
provide the desired amount of slip.
Shift Pressure Solenoid -The Shift Pressure
Solenoid is activated when the TCM determines
that a transmission shift is required. The solenoid
is PWM controller to allow the proper amount of
hydraulic pressure to the shift elements. The sole-
noid is only activated during the shifting of the
transmission. When the solenoid is activated, hy-
draulic pressure is removed from the proper shift
elements to allow the desired shift. Once the shift is
completed, the solenoid is turned off.
Modulation pressure solenoid -The modulation
pressure is always active. The solenoid is pulse
width modulated (PWM) controlled and is used to
modulate the hydraulic system pressure to the
desired pressure.
3.2.4 TRANSMISSION COMPONENT
DESCRIPTIONS
Shift Assembly
The Shift Lever Selector transmits all selector lever
positions, as well as selected shift ranges to the
TCM over the CAN Bus. At the same time, the
selector lever positions P, R, N, and D are transmit-
ted by a cable to the selector lever shaft in the
transmission.
Brake shift inter-lock
To prevent unauthorized shifting out of the park
position, the Selector lever is locked in the Park
position until the ignition key is turned to the run
position and the brake pedal is pressed. This will
allow the driver to shift out of the park position.
Reverse Lamp Output
The Reverse Light Switch is integrated into the
shifter module and controls the reverse lights.
Reverse Inhibitor
The Shift Lever Assembly constantly monitors ABS
wheel speed to prevents an inadvertent selection of
reverse at speeds above approximately 6.4 Km/h(4MPH). The Reverse inhibitor is part of the Shift
Lever Assembly and is controlled by the Shift Lever
Assembly module.
Trans temp sensor - P/N Switch circuit
The TCM will detect the selector lever in park and
neutral positions. The TCM does this by monitoring
the Transmission temperature sensor signal along
with the shifter position signals. The P/N switch
contact is operated by a cam located in the trans-
mission which, opens a reed contact switch that is
wired in series with the transmission temperature
sensor. When the P/N contact switch is opened in
park and neutral, the TCM senses a high transmis-
sion temperature. Confirming the P/N switch sta-
tus. Note: In park or neutral, the TCM uses engine
temperature (to avoid setting a DTC). The TCM
sends a hardwired signal to the ECM that will allow
the ECM controlled start circuit to engage in P or N
only. The TCM also sends a P/N bus message to the
ECM to confirm the P/N switch status.
The Normal Transmission Temperature Sensor
resistance is between 500.0 and 2500.0 ohms.
The normal voltage limits for the transmis-
sion temperature sensor, are between 0.5 and
3.0 volts.
Input Speed Sensors
The NAG1 transmission has two input speed sen-
sors N2 and N3, both speed sensors are located on
the valve body and report DTC's for the input speed
sensors errors. The speed sensors are Hall Effect
speed sensors that are used by the TCM to calculate
the transmissions input speed. Since the input
speed could not be measured directly, two of the
drive elements are measured. Two input speed
sensors were required because both drive elements
are not active in all gears. The input sensors N2 and
N3 will report the same input speed in gears 2nd,
3rd or 4th. If the N2 and N3 input speed signals are
not the same in these gears then there is an issue
with the transmission and the DTC Input Sensors
Mismatch will be set.
The N3 input speed is not reported in1st and 5th
gears. The N2 sensor is not reported in Reverse.
The Input Speed Sensor Overspeed is a rationality
check that is intended to indicate a major transmis-
sion failure and will cause a loss of drive (place the
transmission in Neutral)
Output Speed Sensor (ABS signal)
The NAG1 transmission does not have an output
shaft speed sensor. The TCM uses the ABS (An-
tilock Brake System) Wheel Speed sensor informa-
tion, it receives over the CAN bus, to calculate the
transmissions output shaft speed. The TCM moni-
tors the ABS system for functionality and reports
ABS speed sensor and communication DTCs, which
will affect proper transmission operation.
3
GENERAL INFORMATION

Emergency running function
If DTCs occur, safe-driving conditions must be re-
tained but full functionality of the transmission will
be limited to avoid damaging the automatic trans-
mission. In the event of certain DTCs the TCM
switches to emergency running. The TCM will store
the appropriate DTC codes and solenoids will be
de-energized (turned off)
The transmission effects will be:
²The last gear shifted remains in that position
²The modulating pressure and shift pressure in-
crease to maximum value
²The torque converter clutch is disengaged
(turned off)
Shifting manually after a DTC detection
NOTE: The vehicle can still be shifted
manually to 2nd or reverse gear.
To accomplish these shifts you must
Stop the vehicle
Turn the ignition off
Start the engine
Place the selector lever into D for 2nd gear
Place the selector lever into R for reverse gear
The emergency running function is retained until
the DTC is eliminated or the stored DTC code is
erased.
Stored (Intermittent) DTCs can be reset by cy-
cling the ignition switch
3.3.3 TROUBLE CODE ERASURE
Diagnostic Trouble Codes can be erased in two
ways. The first is to erase the DTC with the DRBIII
or scan tool. The second is if the DTC is no longer
present, the DTC is reset by the TCM (after an
ignition cycle), which will place the DTC in an
intermittent status (Stored DTC).
When there are no diagnostic trouble codes
stored in memory, the DRBIIItwill display
(NO DTC's DETECTED(
3.4 USING THE DRBIIIT
Refer to the DRBIIItuser's guide for instructions
and assistance with reading trouble codes, erasing
trouble codes, and other DRBIIItfunctions.
3.5 DRBIIITERROR MESSAGES
Under normal operation, the DRBIIItwill display
one of only two error messages:
± User-Requested WARM Boot
± User-Requested COLD Boot
If the DRBIIItshould display any other error
message, record the entire display and call the
S.T.A.R. Center.
3.5.1 DRBIIITDOES NOT POWER UP
(BLANK SCREEN)
If the LED's do not light or no sound is emitted at
start up, check for loose cable connections or a bad
cable. Check the vehicle battery voltage. A mini-
mum of 11 volts is required to adequately power the
DRBIIIt.
If all connections are proper between the DRBI-
IItand the vehicle or other devices, and the vehicle
battery is fully charged, an inoperative DRBIIIt
may be the result of faulty cable or vehicle wiring.
For a blank screen, refer to the appropriate Body
Diagnostic manual.
3.5.2 DISPLAY IS NOT VISIBLE
Low temperatures will affect the visibility of the
display. Adjust the contrast to compensate for this
condition.
4.0 DISCLAIMERS, SAFETY,
AND WARNINGS
4.1 DISCLAIMERS
All information, illustrations, and specifications
contained in this manual are based on the latest
5
GENERAL INFORMATION

²Disconnect the live test lead before disconnecting
the common test lead.
²When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interference.
4.3 WARNINGS
4.3.1 VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make
sure the ignition is9lock9position. Failure to do so
could damage the module.
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation: this will damage the wire and eventu-
ally cause the wire to fail because of corrosion.
Be careful when performing electrical tests so as
to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a
second DTC could be set, making diagnosis of the
original problem more difficult.
When replacing a blown fuse, it is important to
use only a fuse having the correct amperage rating.
The use of a fuse with a rating other than indicated
may result in a dangerous electrical system over-
load. If a properly rated fuse continues to blow, it
indicates a problem in the circuit that must be
corrected.
4.3.2 ROAD TESTING A COMPLAINT
VEHICLE
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
DTC or symptom condition.
CAUTION: Before road testing a vehicle, be
sure that all components are reassembled.
During the test drive, do not try to read
DRBIIITscreen while in motion. Do not hang
the DRBIIITfrom the rear view mirror or
operate it yourself. Have an assistant
available to operate the DRBIIIT.
Road testing is an essential step in the diagnostic
process that must not be overlooked. Along with the
diagnostic information obtained from the DRBIIIt
Scan Tool and the original customer concern, the
road test helps verify the problem was current and
any repairs performed, fixed the vehicle correctly.
Always operate and observe the vehicle under ac-
tual driving conditions.
Just as important as the road test is, there are
preliminary inspections that should be performed
prior to the road test. Always check the fluid leveland condition before taking the vehicle on a road
test. Determine if the incorrect fluid is being used,
improper fluid will result in erratic transmission
operation.
Some of the conditions of incorrect fluid level are as
follows:
²Delayed engagement
²Poor shifting or erratic shifting
²Excessive noise
²Overheating
The next step is to verify that the shift linkage is
correctly adjusted. If the shift linkage is incorrectly
adjusted, a number of complaints can result.
The TCM monitors the Shift Lever Position (SLP)
continuously. If the linkage is incorrectly adjusted,
the TCM will sense a shift lever position that is not
correct for the gear chosen by the driver. This may
cause a DTC to be set.
The following complaints may also be the result of
an incorrectly adjusted or worn linkage:
²Delayed clutch engagement
²Erratic shifts
²Vehicle will drive in neutral
²Engine will not crank in park or neutral
²Gear shift linkage will be able to be shifted
without the key in the ignition
²Not able to remove the ignition key in park
²Parking pawl will not engage properly
The shift linkage should also be adjusted when
replacing the Transmission, repairing the valve
body, or when repairing any component between the
shift lever and the Transmission.
Some questions to ask yourself when performing
the road test are as follows:
²Is the complaint or concern what you think the
problem is, based on the drivers description of the
problem?
²Is the Transmission operating normally, or is
there a real problem?
²When does the problem occur?
²Is the problem only in one gear range?
²What temperature does the problem occur?
²Does the vehicle have to sit over night for the
problem to occur?
²Does the transmission go into Limp-in mode?
4.4.4 BULLETINS AND RECALLS
Always perform all Safety Recalls and Technical
Service Bulletins that are applicable to the prob-
lem.
7
GENERAL INFORMATION

5.0 REQUIRED TOOLS AND
EQUIPMENT
> DRBIIIt(diagnostic read-out box) - DRBIIIt
must use the latest release level.
> Jumper wires
> Test Light
> Ohmmeter
> Voltmeter
6.0 GLOSSARY OF TERMS
6.1 ACRONYMS
ABSAntilock Braking system
A/CAir conditioner
A/DAnalog to Digital conversion
APPAccelerator Pedal Position
CANController Area Network (Vehicle
Bus System)
CKTCircuit
DLCData Link Connector
DRBIIItDiagnostic Readout Box
DTCDiagnostic Trouble Code
ECMDiesel Engine Controller
EMCCElectronically Modulated Converter
Clutch
IODIgnition off-draw
ISSInput Speed Sensor (N2 and N3)
KK line communication bus
LEDLight Emitting Diode
MILMalfunction Indicator LampOSSOutput Speed Sensor (derived from
the ABS controller)
PEMCCPartial Electronically Modulated
Converter Clutch
PWMPulse width modulated
SKREEMSentry Key Remote Entry Module
SLAShift Lever Assembly
SWSwitch
TCCTorque Converter Clutch
TCMTransmission Control Module
TPThrottle Position
TRDTorque Reduction
TTSTransmission Temperature Sensor
1-2/4-5
solenoidcontrols the shift into and out of
2nd gear or 5th gear.
V2-3 so-
lenoidcontrols the shift into and out of 3rd
gear
V3-4 so-
lenoidcontrols the shift into and out of 4th
gear
VTCC
solenoidis pulse width modulated and con-
trols the TCC clutch
Shift
Pressure
Solenoidis a pulse width modulated solenoid
and controls the hydraulic pressure
to the shift elements.
Modula-
tion
pressure
solenoidis a pulse width modulated solenoid
and controls the hydraulic system
pressure
6.2 DEFINITIONS
Driving cycle counter) -The starts since first set
counter indicates the number of driving cycles since
the first occurrence of an error.
8
GENERAL INFORMATION

TEST ACTION APPLICABILITY
2 Ignition on, engine not running.
With the DRBIIIt, read Transmission DTCs.
Are there any Transmission Solenoid DTCs present?All
Ye s!Refer to the Transmission category and perform the appropriate
symptom.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 3
3 With the DRBIIIt, read ABS DTCs.
Are there any ABS DTCs present?All
Ye s!Refer to the ABS category and perform the appropriate symptom.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 4
4 Remove and inspect the Transmission Valve Body and Electrohydraulic Control Unit
Assembly per the Service Information.
NOTE: This DTC is usually set due to a internal transmission problem such
as but not limited to: stuck solenoid or valve and/or contamination in the
valve body, broken springs, leaking clutch seals, dislodged or broken snap
ring.
Inspect internal transmission per the Service Information.
Where there any problems found?All
Ye s!Repair internal transmission as necessary. Refer to the Service
Information for the proper repair procedure.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Replace the Transmission Control Module.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
75
TRANSMISSION - NAG1
IMPROPER GEAR ÐContinued

Symptom:
TCC OVER TEMP
When Monitored and Set Condition:
TCC OVER TEMP
When Monitored: Solenoid supply active. No Input Speed Sensor N2 - N3, CAN C Bus,
PCM/ECM, CAN Engine, CAN Engine Speed DTCs present. Torque Converter Clutch in
slip mode.
Set Condition: Friction loss factor reaches threshold.
POSSIBLE CAUSES
INTERNAL TRANSMISSION
TEST ACTION APPLICABILITY
1NOTE: Low fluid level can be the cause of many transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the service information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIIIt, read the engine DTCs. Check and repair all engine DTCs prior to
performing transmission symptom diagnostics.
With the DRBIIIt, read and record all Transmission DTCs.
NOTE: Check connectors - Clean/repair as necessary. Poor pin to terminal
connections can set DTCs.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Most DTCs set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
Note: Verify flash level of transmission controller. Some problems are
corrected by software upgrades to the transmission controller.
NOTE: Check for any Technical Service Bulletins that may apply.
Perform this procedure prior to Symptom diagnosis.All
Continue
Go To 2
2 This DTC is an informational DTC.
Check for any TSBs or Controller updates that may apply.
This is usually a sign of TCC failure or internal transmission problems.
Check the Engine and Transmission Cooling Systems for proper operation.
View repair.All
Repair
Repair internal Transmission as necessary. Refer to the Service
Information for proper repair procedure.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
111
TRANSMISSION - NAG1