2006 MERCEDES-BENZ SPRINTER ECO mode

Two O-rings on the male half of the fitting are
used to seal the connection. These O-rings are com-
patible with R-134a refrigerant and must be replaced
with O-rings made of the same material.
Secondary clips are installed over the two con-
nected coupler halves at the factory for added blowoff
protection. In addition, some models have a plastic
ring that is used at the factory as a visual indicator
to confirm that these couplers are connected. After
the coupler is connected, the plastic indicator ring is
no longer needed; however, it will remain on the
refrigerant line near the coupler cage.
REMOVAL
WARNING: Refer to the applicable warnings and
cautions for this system before performing the fol-
lowing operation (Refer to 24 - HEATING & AIR
CONDITIONING/PLUMBING - WARNINGS) and (Refer
to 24 - HEATING & AIR CONDITIONING/PLUMBING -
CAUTIONS). Failure to follow the warnings and cau-
tions could result in possible personal injury or
death.
(1) Recover the refrigerant from the refrigerant
system (Refer to 24 - HEATING & AIR CONDITION-
ING/PLUMBING - STANDARD PROCEDURE -
REFRIGERANT SYSTEM RECOVERY).
(2) Remove the secondary retaining clip from the
spring-lock coupler.
(3) Fit the proper size A/C line disconnect tool
(Special Tool Kit 7193) over the spring-lock coupler
cage (Fig. 38).(4) Close the two halves of the A/C line disconnect
tool around the spring-lock coupler.
(5) Push the A/C line disconnect tool into the open
side of the coupler cage to expand the garter spring.
Once the garter spring is expanded and while still
pushing the disconnect tool into the open side of the
coupler cage, pull on the refrigerant line attached to
the female half of the coupler fitting until the flange
on the female fitting is separated from the garter
spring and cage on the male fitting within the dis-
connect tool.
NOTE: The garter spring may not release if the A/C
line disconnect tool is cocked while pushing it into
the coupler cage opening.
(6) Open and remove the A/C line disconnect tool
from the disconnected spring-lock coupler.
(7) Complete the separation of the two halves of
the coupler fitting.
INSTALLATION
(1) Check to ensure that the garter spring is
located within the cage of the male coupler fitting,
and that the garter spring is not damaged.
(a) If the garter spring is missing, install a new
spring by pushing it into the coupler cage opening.
(b) If the garter spring is damaged, remove it
from the coupler cage with a small wire hook (DO
NOT use a screwdriver) and install a new garter
spring.
(2) Clean any dirt or foreign material from both
halves of the coupler fitting.
(3) Install new O-rings on the male half of the cou-
pler fitting.
Fig. 37 Spring-Lock Coupler - Typical
1 - MALE HALF SPRING-LOCK COUPLER
2 - FEMALE HALF SPRING-LOCK COUPLER
3 - SECONDARY CLIP
4 - CONNECTION INDICATOR RING
5 - COUPLER CAGE
6 - GARTER SPRING
7 - COUPLER CAGE
8 - O-RING SEALS
Fig. 38 Refrigerant Line Spring-Lock Coupler
Disconnect
VAPLUMBING 24 - 99

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

The NAG1 will default in the current gear position
if a DTC is detected, then after a key cycle or shift
to park the transmission will go into Limp-in, which
is mechanical 2nd gear. Some DTC's may allow the
transmission to resume normal operation (recover)
if the detected problem goes away. Permanent
limp-in DTC will recover when the key is cycled, but
if the same DTC is detected for three key cycles the
system will not recover and the DTC must be
cleared from the TCM with the DRBIII scan tool.
Once the DRBIIItis in the Transmission portion
of the diagnostic program, it constantly monitors
the TCM to see if the system is in limp-in mode. If
the transmission is in limp-in mode, the DRBIIIt
will flash the red LED.
3.2.1 CONTROLLER MODES OF
OPERATION
Permanent limp-in mode
When the TCM determines there is a non-
recoverable condition present that will not allow
proper transmission operation, it will place the
transmission in permanent limp-in mode. When the
condition occurs the TCM will turn off all solenoids
as well as the solenoid supply output circuit. If this
occurs while the vehicle is moving, the transmission
will remain in the current gear until the ignition is
turned off or shifter is placed in the9P9position.
Once the shifter has been placed in9P9the Trans-
mission will only allow 2nd gear operation. If the
problem occurs while the vehicle is not moving the
transmission will only allow 2nd gear operation.
Temporary limp-in mode
This mode is the same as the permanent limp-in
mode except if the condition is no longer present the
system will resume normal operation. (Recoverable
DTC)
Undervoltage limp-in mode
When the TCM detects that system voltage has
dropped below 8.5 volts it will disable voltage de-
pendant diagnostics and place the transmission in
the temporary limp-in mode. When the TCM senses
that the voltage has risen above 9.0 volts, normal
transmission operation will be resumed.
Hardware Error Mode
When the TCM detects a major internal error the
transmission will be placed in the permanent
limp-in mode and cease all communication over the
CAN bus. Once the TCM has entered this mode
normal transmission operation will not resume un-
til all DTC's are cleared from the TCM.
Loss of Drive
If the TCM detects a situation that has resulted or
may result in engine or transmission failure, the
transmission will be placed in the neutral position.Improper Ratio, Input Sensor Overspeed, or Engine
Overspeed DTC's will cause the loss of drive.
Controlled Limp-in Mode
When a failure condition does not require the TCM
to shut down the solenoid supply, but the failure is
of a degree where the TCM will place the transmis-
sion into a predefined gear, there will be several
shift performance issues. Examples of this are, with
the transmission slipping the controller will at-
tempt to place the transmission into third gear and
maintain third gear for all forward drive conditions.
Another example is some of the CAN bus message
issues if the TCM does not receive required infor-
mation from the Engine Controller, then default
values are used which may result in poor transmis-
sion shift performance.
3.2.2 MIL ILLUMINATION
For failures detected by the Transmission Con-
troller that result in the controller placing the
transmission into a limp-in mode, except for System
Overvoltage and System Undervoltage DTCs, the
MIL will be illuminated. The Transmission Control
Module will inform the ECM over the CAN bus that
a failure has occurred. The ECM will illuminate the
MIL. If the condition is removed and the failure
becomes Stored (Intermittent), the Transmission
controller will stop reporting that the DTC is active
and the ECM will extinguish the MIL.
NOTE: The MIL will light when the problem is
first detected and it will not go off until the
next ignition cycle, after all problem
conditions have been checked for their
presence. This normally takes several
minutes of driving.
3.2.3 SOLENOIDS
1-2/4-5 solenoid -The 1-2/4-5 solenoid is activated
when the TCM determines that the transmission
must shift into or out of 2nd gear or 5th gear. The
solenoid is only activated during the shifting of the
transmission. When the solenoid is activated, hy-
draulic pressure is applied to the proper shift ele-
ments in the transmission to allow the desired shift.
Once the shift is completed, the solenoid is turned
off.
2-3 solenoid -The 2-3 solenoid is activated when
the TCM determines that the transmission must
shift into or out of 3rd 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.
2
GENERAL INFORMATION

3.2.5 TRANSMISSION OPERATION AND
SHIFT SCHEDULING
The transmission covered in this manual has
unique shift schedules depending on the tempera-
ture of the transmission oil. The transmission oil
temperature has a decisive effect on the shift qual-
ity of the transmission. The shift schedule is modi-
fied to extend the life of the transmission while
operating under extreme conditions and to improve
driver comfort by modifying shift schedules.
The transmission oil temperature is measured
with a Temperature Sensor on the NAG1 transmis-
sion. The Temperature Sensor is an integral com-
ponent of the Transmission Solenoid assembly. If
the Temperature Sensor is causing a problem, a
DTC will be set in the TCM.
The Transmission Temperature Sensor is wired in
series with the Park /Neutral (P/N) switch. The P/N
switch is also located in the transmission. The trans-
mission temperature is only read by the TCM when
the P/N switch closes while in the R, D position.
When the shifter lever is in the park or neutral
position, the P/N switch opens and the temperature
being displayed is Engine temperature.
AutoStick Feature (If equipped)
This feature allows the driver to manually shift the
transaxle when the shift lever is moved sideways to
the (+ / -) in position D to adjust the shift range.
3.2.6 TRANSMISSION ADAPTIVES -
INITIALIZE AND STORE
Initialize Adaptive -This TCM function should be
used when a new transmission has been placed in
the vehicle. This command will reset the TCM
adaptive to the factory setting.
Store Adaptive -This command should be used
after the vehicle has been test driven by the tech-
nician to store any learned adaptive changes that
occurred during the test drive. During normal op-
eration adaptive are updated every 10 minutes.
Using this command the latest adaptive will be
written to the TCM immediately.
3.3 DIAGNOSTIC TROUBLE CODES
Diagnostic trouble codes (DTC's) are codes stored
by the Transmission Control Module (TCM) and the
Shift Lever Assembly Module (SLA) to help diag-
nose Transmission and Shifter problems. They are
viewed using the DRBIIItscan tool.
Always begin by performing a visual inspection of
the wiring, connectors, cooler lines and the trans-
mission. Any obvious wiring problems or leaks
should be repaired prior to performing any diagnos-
tic test procedures. Some engine driveability prob-lems can be misinterpreted as a transmission prob-
lem. Ensure that the engine is running properly
and that no ECM DTC's are present that could
cause a transmission complaint.
If there is a communication K-ABS,Shifter or
K-TCM circuit problem, trouble codes will not be
accessible until the problem is fixed. The DRBIIIt
will display an appropriate message. The following
is a possible list of causes for a bus problem:
± open or short to ground/battery in K line
circuit.
± internal failure of any module or component
connected to the K line circuit
Each diagnostic trouble code is diagnosed by
following a specific testing sequence. The diagnostic
test procedures contain step-by-step instructions
for determining the cause of a transmission diag-
nostic trouble code. Possible sources of the code are
checked and eliminated one by one. It is not neces-
sary to perform all of the tests in this book to
diagnose an individual code. These tests are based
on the problem being present at the time that the
test is run.
If the TCM records a DTC that will adversely
affect the vehicles transmission, it will request (via
the communication bus) that the ECM illuminate
the Malfunction Indicator Lamp (MIL). All trans-
mission DTC's will be stored in the TCM.
3.3.1 ACTIVE (HARD) CODE
Any Diagnostic Trouble Code (DTC) that is set
whenever the system or component is monitored is
an Active code. This means that the problem is
there every time the TCM checks that system or
component. Some codes will set immediately at
start up and others will require a road test under
specific conditions to set the DTC. It must be
determined if a code is Active (repeatable) or Stored
(Intermittent) before attempting diagnosis.
3.3.2 STORED (INTERMITTENT) CODE
A diagnostic trouble code that is not there every
time the TCM checks the circuit or function is a
Stored (Intermittent) code. Problems that come and
go like this are the most difficult to diagnose, they
must be looked for under the specific conditions
that cause them. If the DTC is reset (after an
ignition cycle) the DTC will be set to Stored (Inter-
mittent) status. A DTC status can be9Active9or
9Stored9(Intermittent). Active is when the DTC is
present in the controller and the transmission is in
the particular mode of operation for that DTC.
Stored means that the DTC occurred at some point,
but is not currently present, or the conditions have
not been right to check for the presence of the
problem, when a DTC is classified as Stored (Inter-
mittent), no TCM reaction is required.
4
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:
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

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