service 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

information available at the time of publication.
The right is reserved to make changes at any time
without notice.
4.2 SAFETY
4.2.1 TECHNICIAN SAFETY INFORMATION
WARNING: ENGINES PRODUCE CARBON
MONOXIDE THAT IS ODORLESS, CAUSES
SLOWER REACTION TIME, AND CAN LEAD
TO SERIOUS INJURY. WHEN THE ENGINE IS
OPERATING KEEP SERVICE AREAS WELL
VENTILATED OR ATTACH THE VEHICLE
EXHAUST SYSTEM TO THE SHOP EXHAUST
REMOVAL SYSTEM.
Set the parking brake and block the wheels before
testing or repairing the vehicle. If is especially
important to block the wheels on front-wheel drive
vehicles: the parking brake does not hold the drive
wheels.
Some operations in this manual require that
hydraulic tubes, hoses, and fittings, disconnected
for inspection or testing purposes. These systems,
when fully charged, contain fluid at high pressure.
Before disconnecting any hydraulic tubes, hoses,
and fittings, be sure that the system is fully depres-
surized.
When servicing a vehicle, always wear eye pro-
tection, and remove any metal jewelry such as
watchbands or bracelets that might make an inad-
vertent electrical contact.
When diagnosing a Transmission system prob-
lem, it is important to follow approved procedures
where applicable. These procedures can be found in
the service information. Following these procedures
is very important to the safety of individuals per-
forming diagnostic tests.
4.2.2 VEHICLE PREPARATION FOR
TESTING
Make sure the vehicle being tested has a fully
charged battery. If it does not, false diagnostic
DTC's or error messages may occur. It is extremely
important that accurate shift lever position data is
available to the TCM. The accuracy of any DTC
found in memory is doubtful unless the Shift Lever
Test, performed on the DRBIIItScan Tool, passes
without failure.
4.2.3 SERVICING SUB-ASSEMBLIES
Some components of the Transmission system are
intended to be serviced in assembly only. Attempt-
ing to remove or repair certain system sub-
components may result in personal injury and/orimproper system operation. Only those components
with approved repair and installation procedures in
the service information should be serviced.
4.2.4 DRBIIITSAFETY INFORMATION
WARNING: EXCEEDING THE LIMITS OF THE
DRBIIITMULTIMETER IS DANGEROUS. IT
CAN EXPOSE YOU TO SERIOUS OR
POSSIBLY FATAL INJURY. CAREFULLY
READ AND UNDERSTAND THE CAUTIONS
AND THE SPECIFICATION LIMITS.
²Follow the vehicle manufacturer's service speci-
fications at all times.
²Do not use the DRBIIItif it has been damaged.
²Do not use the test leads if the insulation is
damaged or if metal is exposed.
²To avoid electrical shock, do not touch the test
leads, tips or the circuit being tested.
²Choose the proper range and function for the
measurement. Do not try voltage or current mea-
surements that may exceed the rated capacity.
²Do not exceed the limits shown in the table.
FUNCTION INPUT LIMIT
Volts 0-500 volts peak AC
0-500 volts DC
Ohms (resistance)* 0-1.12 megohms
Frequency measured
Frequency generated0-10 khz
Temperature -58-1100ÉF
-50-600C
*Ohms cannot be measured if voltage is present.
Ohms can be measured only in a non-powered
circuit.
²Voltage between any terminal and ground must
not exceed 500v DC or 500v peak AC.
²Use caution when measured voltage above 25v
DC or 25v AC.
²The circuit being tested must be protected by a
10A fuse or circuit breaker.
²Use the low current shunt to measure circuits up
to 10A. Use the high current clamp to measure
circuits exceeding 10A.
²When testing for the presence of voltage or cur-
rent, make sure the meter is functioning cor-
rectly. Take a reading of a known voltage or
current before accepting a zero reading.
²When measuring current, connect the meter in
series with the load.
6
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

Symptom:
*NO RESPONSE FROM SHIFTER ASSEMBLY
POSSIBLE CAUSES
CHECK POWERS AND GROUNDS TO THE SHIFTER ASSEMBLY
CONTROLLER ANTILOCK BRAKE
K-ABS, SHIFTER ASSEMBLY CIRCUIT SHORTED TO GROUND
CONTROLLER ANTILOCK BRAKE
K-ABS, SHIFTER ASSEMBLY CIRCUIT SHORTED TO VOLTAGE
K-ABS, SHIFTER ASSEMBLY CIRCUIT OPEN
SHIFTER ASSEMBLY
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Shifter Assembly harness connector.
Check each power and ground circuit to the module.
Were any problems found?All
Ye s!Refer to the wiring diagrams located in the service information to
help isolate an open or shorted condition. Repair as necessary.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 2
2 Turn the ignition off.
Disconnect the Shifter Assembly harness connector.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance between ground and the K-ABS, Shifter Assembly circuit.
Is the resistance below 5.0 ohms?All
Ye s!Go To 3
No!Go To 4
3 Turn the ignition off.
Disconnect the CAB harness connector.
Measure the resistance between ground and the K-ABS, Shifter Assembly circuit.
Is the resistance below 5.0 ohms?All
Ye s!Repair the K-ABS, Shifter Assembly circuit for a short to ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Replace the Controller Antilock Brake in accordance with the
service information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
10
COMMUNICATION

TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the DRBIIItfrom the DLC.
Disconnect the Shifter Assembly harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-ABS, Shifter Assembly
circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Go To 5
No!Go To 6
5 Turn the ignition off.
Disconnect the Controller Antilock Brake harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-ABS, Shifter Assembly
circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Repair the K-ABS, Shifter Assembly circuit for a short to voltage.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Replace the Controller Antilock Brake in accordance with the
service information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
6 Turn the ignition off.
Disconnect the Shifter Assembly harness connector.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance of the K-ABS, Shifter Assembly circuit between the Shifter
Assembly connector and the DLC.
Is the resistance below 5.0 ohms?All
Ye s!Replace the Shifter Assembly in accordance with the Service
Information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Repair the K-ABS, Shifter Assembly circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
11
COMMUNICATION
*NO RESPONSE FROM SHIFTER ASSEMBLY ÐContinued

Symptom:
*NO RESPONSE FROM TRANSMISSION CONTROL MODULE
POSSIBLE CAUSES
CHECK POWERS AND GROUNDS TO THE TRANSMISSION CONTROL MODULE
K-TCM CIRCUIT SHORTED TO GROUND
K-TCM CIRCUIT SHORTED TO VOLTAGE
K-TCM CIRCUIT OPEN
TRANSMISSION CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the Transmission Control Module harness connectors.
Check each power and ground circuit to the module.
Were any problems found?All
Ye s!Refer to the wiring diagrams located in the service information to
help isolate an open or shorted condition. Repair as necessary.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 2
2 Turn the ignition off.
Disconnect the TCM harness connectors.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance between ground and the K-TCM circuit.
Is the resistance below 5.0 ohms?All
Ye s!Repair the K-TCM circuit for a short to ground.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 3
3 Turn the ignition off.
Disconnect the DRBIIItfrom the DLC.
Disconnect the TCM harness connectors.
Turn the ignition on.
Using a 12-volt test light connected to ground, probe the K-TCM circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Repair the K-TCM circuit for a short to voltage.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Go To 4
12
COMMUNICATION

TEST ACTION APPLICABILITY
4 Turn the ignition off.
Disconnect the TCM harness connectors.
Disconnect the DRBIIItfrom the DLC.
Measure the resistance of the K-TCM circuit between the TCM connector and the
DLC.
Is the resistance below 5.0 ohms?All
Ye s!Replace the Transmission Control Module in accordance with the
Service Information.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
No!Repair the K-TCM circuit for an open.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1.
13
COMMUNICATION
*NO RESPONSE FROM TRANSMISSION CONTROL MODULE ÐContinued

Symptom:
BACKUP LAMP CKT SHORT TO GROUND
POSSIBLE CAUSES
BACKUP LAMP CIRCUIT SHORT TO GROUND
SHIFT LEVER ASSEMBLY
TEST ACTION APPLICABILITY
1 Turn the ignition off to the lock position.
Disconnect the Shift Lever Assembly harness connector.
Isolate the Backup Lamp circuit, remove the Backup Lamp bulbs.
NOTE: Check Backup Lamp bulbs and socket for a short or corrosion.
Measure the resistance between ground and the Backup Lamp circuit.
Is the resistance below 5.0 ohms?All
Ye s!Repair the Backup Lamp circuit for a short to ground.
No!Replace the Shift Lever Assembly per the Service Information.
14
SHIFT LEVER ASSEMBLY

Symptom:
BACKUP LAMP CKT SHORT TO VOLTAGE OR OPEN
POSSIBLE CAUSES
BACKUP LAMP CIRCUIT OPEN
BACKUP LAMP CIRCUIT SHORT TO VOLTAGE
SHIFT LEVER ASSEMBLY
TEST ACTION APPLICABILITY
1 Start the engine.
While back probing, measure the voltage of the Backup Lamp circuit.
Is the voltage above 0.5 volts?All
Ye s!Go To 2
No!Go To 3
2 Turn the ignition off to the lock position.
Disconnect the Shift Lever Assembly harness connector.
Start the engine.
Measure the voltage of the Backup Lamp circuit in the Shift Lever Assembly harness
connector.
Is the voltage above 0.5 volts?All
Ye s!Repair the Backup Lamp circuit for a short to voltage.
No!Replace the Shift Lever Assembly per the Service Information.
3 Turn the ignition off to the lock position.
Disconnect the Shift Lever Assembly harness connector.
Remove the Backup Lamp bulb(s).
Connect a jumper wire between Shift Lever Assembly circuit and B(+).
Using a 12-volt test light connected to 12-volts, check the Backup Lamp circuit in the
Backup Lamp socket(s).
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Replace the Shift Lever Assembly per the Service Information.
No!Repair the Backup Lamp circuit for an open.
15
SHIFT LEVER ASSEMBLY

Symptom:
BACKUP LAMP SUPPLY CIRCUIT OPEN
POSSIBLE CAUSES
FUSED IGNITION SWITCH OUTPUT OPEN
SHIFT LEVER ASSEMBLY
TEST ACTION APPLICABILITY
1 Turn the ignition off to the lock position.
Disconnect the Shift Lever Assembly harness connector.
Start the engine.
Using a 12-volt test light connected to ground, check the Fused Ignition Switch
Output circuit.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s!Replace the Shift Lever Assembly per the Service Information.
No!Repair the Fused Ignition Switch Output circuit for an open. If
the fuse is open, make sure to check for a short to ground.
16
SHIFT LEVER ASSEMBLY