2006 MERCEDES-BENZ SPRINTER engine

VA LV E
DESCRIPTION
Exhaust gas recirculation reduces the quantity of
fresh air supplied to the cylinders per stroke without
having to throttle the air supply. Exhaust gas is
recirculated during all engine speed and engine load
conditions. As a result, emissions are reduced. If a
quantity of exhaust gas is mixed with the air that is
to be used to burn the fuel in the cylinders, the oxy-
gen content is reduced because the exhaust gas is
low in oxygen. The result is that the combustion rate
is reduced, as is the combustion temperature. This
reduces the quantity of NOx that are emitted in the
exhaust gas. (Fig. 2).
The ECM power supply relay has a power off delay
feature. The relay is powered off approximately 15
seconds after the ignition switch is turned off. This
allows for the self-cleaning function of the EGR valve
and a function check of the sensors for diagnosis pur-
poses.
Fig. 1 EGR AND COOLER
1 - EGR VALVE 3 - COOLING FINS
2 - COOLANT PASSAGE 4 - EXHAUST GAS PASSAGE
VAEXHAUST GAS RECIRCULATION 25 - 5

OPERATION
The mass of the air supplied to the cylinders per
stroke is the decisive factor for determining the opti-
mum quantity of exhaust gas for the operating con-
dition. This is calculated from the Mass Air Flow
sensor information.
The ECM evaluates this signal as well as that
from the Charge Air Pressure sensor, and outputs a
PWM signal in accordance with one of the maps
stored in it. The signal is sent to the exhaust gas
recirculation valve. The map is formulated to keep
the NOx as low as possible. The EGR valve is actu-
ated by an electric positioning motor and has a self
cleaning function. Every time the ignition switch is
turned off, the valve rotates twice to eliminate any
carbon deposits.
REMOVAL
NOTE: The EGR and EGR Cooler are serviced as an
assembly.
(1) Disconnect the negative battery cable.
(2) Partailly drain the cooling system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(3) Lift up on the charge air hose retaining clip at
the intake manifold and disconnect hose with seal
(4) Disconnect the electrical connector at the EGR
positioner (Fig. 3).(5) Disconnect the EGR cooler hose.
(6) Remove the EGR fasteners and EGR with
cooler assembly (Fig. 3).
INSTALLATION
(1) Clean all gasket mating surfaces.
(2) Position the EGR positioner to the intake man-
ifold with a new gasket, install bolts and tighten to
124 lbs.in (14 N´m) (Fig. 3).
(3) Connect the EGR positioner electrical connec-
tor (Fig. 3).
(4) Inspect the seal of the charge air inlet tube,
replace as necessary (Fig. 3).
(5) Seat the charge air tube with gasket into the
intake manifold and push down on the charge air
tube retaining clip.
(6) Refill the cooling system (Refer to 7 - COOL-
ING/ENGINE/COOLANT - STANDARD PROCE-
DURE).
(7) Connect negative battery cable.
VALVE COOLER
DESCRIPTION
The exhaust gas recirculation (EGR) cooler is an
integrated part of the EGR valve. Coolant flows
around the exhaust gasses, cooling them before they
are remixed with the incoming air and reburned in
the combustion chamber (Fig. 4).
Fig. 2 EXHAUST GAS RECIRCULATION
1 - E G R VA LV E
2 -CHARGE AIR PRESSURE SENSOR
3 - EXHAUST MANIFOLD
4 - EGR DUCT IN CYLINDER HEAD
5 - INTAKE MANIFOLD
Fig. 3 EGR VALVE
1 - E G R VA LV E
2 - INTAKE MANIFOLD
3 - EGR COOLER HOSE
4 - HARNESS CONNECTOR
25 - 6 EXHAUST GAS RECIRCULATIONVA

INDEX
ABS INDICATOR.......................8J-9ACCELERATOR PEDAL POSITION SENSOR. . . 14-32
ACCESSORY SWITCH BEZEL............23-56
ADR INDICATOR.....................8J-10
AIR CLEANER ELEMENT................9-21
AIR CLEANER HOUSING................9-21
AIR FILTER ....................24-45, 24-58
AIR OUTLET TEMPERATURE SENSOR....24-16
AIR OUTLETS.......................24-45
AIRBAG CONTROL MODULE.............8O-8
AIRBAG INDICATOR...................8J-11
ALB CONTROLLER....................5-16
ALB LEVER..........................5-16
AMBIENT TEMPERATURE INDICATOR.....8J-11
AMBIENT TEMPERATURE SENSOR.......24-17
ANTENNA BODY & CABLE..............8A-1
ARMREST..........................23-79
ASH RECEIVER......................23-57
ASH RECEIVER / CIGAR LIGHTER LAMP
UNIT..............................8L-30
ASSIST HANDLE.....................23-71
AUDIO..............................8A-1
AUTOMATIC TRANSMISSION NAG1 -
SERVICE INFORMATION................21-3
A - PILLAR TRIM.....................23-70
A / C CLUTCH RELAY.................24-24
A / C COMPRESSOR CLUTCH COIL.......24-12
A / C COMPRESSOR CLUTCH............24-8
A / C COMPRESSOR..................24-66
A / C CONDENSER COVER.............24-52
A / C CONDENSER FAN RELAY..........24-26
A / C CONDENSER HOUSING...........24-52
A / C CONDENSER....................24-69
A / C CONTROL MODULE..............24-28
A / C DISCHARGE LINE................24-71
A / C EVAPORATOR COVER.............24-55
A / C EVAPORATOR HOUSING...........24-55
A / C EVAPORATOR...................24-72
A / C EXPANSION VALVE...............24-73
A / C HEATER CONTROL...............24-12
A / C HIGH PRESSURE SWITCH.........24-30
A / C LOW PRESSURE SWITCH.........24-32
A / C PRESSURE TRANSDUCER.........24-14
BACKLITE - BULKHEAD TRIM PANEL.....23-84
BACKUP LAMP BULB..................8L-5
BASECOAT / CLEARCOAT FINISH........23-77
BATTERY CABLES....................8F-14
BATTERY HOLDDOWN.................8F-13
BATTERY SYSTEM.....................8F-1
BATTERY TRAY......................8F-16
BATTERY............................8F-6
BEARINGS - DIFFERENTIAL CASE.........3-38
BEARING / SEAL - AXLE HUB............3-28
BEARING / SEAL - AXLE................3-24
BELT TENSIONERS.....................7-5
BLOWER MOTOR RELAY...............24-33
BLOWER MOTOR RESISTOR............24-17
BLOWER MOTOR SWITCH........24-19, 24-35
BLOWER MOTOR...............24-47, 24-58
BODY...............................23-1
BOOST PRESSURE SENSOR............14-33
BRAKE INDICATOR...................8J-12
BRAKE LAMP SWITCH.................8L-6
BRAKE LINES.........................5-8
BRAKE PADS / SHOES...................5-8
BRAKE WEAR INDICATOR..............8J-13
BRAKES - ABS........................5-30
BRAKES - BASE........................5-2
BRAKE / PARK LAMP BULB.............8L-7
BULKHEAD TRIM PANEL...............23-72
BUMPERS...........................13-1
BUSHINGS............................2-3
B - PILLAR TRIM.....................23-71
CABIN HEATER.....................24-104
CABLE TENSIONER....................5-24
CABLE..............................8P-2
CABLES.............................5-24
CAMSHAFT POSITION SENSOR..........14-33
CAMSHAFT(S)........................9-28
CARGO LAMP SWITCH................8L-31
CARGO / DOME LAMP BULB............8L-30
CARGO / DOME LAMP UNIT............8L-31
CARPETS AND FLOOR MATS...........23-72
CATALYTIC CONVERTER
................11-3
CENTER BEARING
......................3-9
CENTER HIGH MOUNTED STOP LAMP BULB. . . 8L-8CENTER HIGH MOUNTED STOP LAMP UN.....8L-8
CENTER ROLLER ARM
................23-36CENTER TRACK......................23-37
CENTRAL TIMER MODULE..............8E-1
CHARGE AIR COOLER AND PLUMBING....11-4
CHARGING INDICATOR................8J-14
CHARGING SYSTEM..................8F-17
CHECK VALVE.......................8R-11
CHECK.......................23-13, 23-23
CHIME / BUZZER......................8B-1
CIGAR LIGHTER OUTLET............8W-97-1
CIRCUIT BREAKER.................8W-97-2
CLEARANCE LAMP BULB...............8L-9
CLEARANCE LAMP UNIT................8L-9
CLOCK.............................8J-14
CLOCKSPRING......................8O-12
CLUSTER BEZEL.....................23-55
COLUMN............................19-4
CONNECTOR.......................Intro.-9
CONNECTOR/GROUND/SPLICE
LOCATION........................8W-91-1
CONTROLLER ANTILOCK BRAKE.........8E-3
COOLANT LEVEL SENSOR...............7-13
COOLANT LOW INDICATOR.............8J-15
COOLANT............................7-9
COOLING.............................7-1
COWL TRIM........................23-73
CRANKCASE VENTILATION BREATHER......25-2
CRANKCASE VENTILATION HEATER.......25-1
CRANKSHAFT OIL SEAL - FRONT.........9-42
CRANKSHAFT OIL SEAL - REAR..........9-41
CRANKSHAFT POSITION SENSOR........14-35
CRANKSHAFT........................9-39
CUP HOLDER........................23-57
CYLINDER HEAD COVER(S).............9-33
CYLINDER HEAD......................9-22
DAYTIME RUNNING LAMP RELAY.......8L-10
DEFROSTER DUCTS..................24-47
DIFFERENTIAL........................3-31
DIODE............................Intro.-9
DISC BRAKE CALIPER ADAPTER.........5-14
DISC BRAKE CALIPERS.................5-11
DOME LAMP / INTRUSION SENSOR
BULB..............................8L-33
DOME LAMP / INTRUSION SENSOR......8L-33
DOME / READING LAMP BULB..........8L-32
DOME / READING LAMP UNIT..........8L-32
DOOR GLASS............23-15, 23-30, 23-46
DOOR JAMB SWITCH.................8L-34
DOOR LOCK MOTOR...................8N-1
DOOR OPENING SEALS................23-90
DOOR........................23-14, 23-23
DRIVE BELTS..........................7-5
DRIVER AIRBAG.....................8O-16
DRIVER HEATED SEAT SWITCH.........8G-11
D - PILLAR TRIM.....................23-73
ELECTRIC COOLANT PUMP.............24-75
ELECTRICAL.........................5-30
ELECTROHYDRAULIC UNIT............21-105
ENGINE BLOCK HEATER................7-14
ENGINE BLOCK.......................9-37
ENGINE CONTROL MODULE.............8E-3
ENGINE COOLANT TEMP SENSOR........7-15
ENGINE COOLANT THERMOSTAT.........7-16
ENGINE CRADLE CROSSMEMBER........13-8
ENGINE TEMPERATURE GAUGE.........8J-15
ENGINE..............................9-2
ENTRY / EXIT LAMP BULB.............8L-34
ENTRY / EXIT LAMP UNIT..............8L-35
ESP INDICATOR......................8J-16
EVAPORATOR TEMPERATURE
SENSOR......................24-19, 24-37
EXHAUST GAS RECIRCULATION..........25-4
EXHAUST MANIFOLD..................9-68
EXHAUST PIPE.......................11-3
EXHAUST SYSTEM....................11-1
EXHAUST TUBE.....................24-105
EXTERIOR HANDLE.......23-16, 23-31, 23-35
FAN DRIVE VISCOUS CLUTCH...........7-17
FASTENER IDENTIFICATION...........Intro.-3
FASTENER USAGE...................Intro.-6
FINESSE SANDING / BUFFING & POLISH . . 23-78
FLOOR DISTRIBUTION DUCTS..........24-47
FLUID AND FILTER..................21-131
FLUID CAPACITIES.....................0-5
FLUID COOLER TUBE
.................19-13
FLUID FILL / CHECK LOCATIONS
..........0-5
FLUID RESERVOIR
....................5-15
FLUID TYPES
..........................0-1
FLYWHEEL
...........................9-43FOG LAMP BULB.....................8L-10
FOG LAMP RELAY....................8L-11
FOG LAMP SWITCH...................8L-12
FRAME..............................13-3
FREEWHEELING CLUTCH.............21-135
FRONT BUMPER - STEPS...............13-2
FRONT DOOR INNER BELT
WEATHERSTRIP.....................23-90
FRONT DOOR OUTER BELT
WEATHERSTRIP.....................23-90
FRONT FASCIA.......................13-2
FRONT LAMP UNIT...................8L-13
FRONT POSITION LAMP BULB..........8L-14
FRONT SEAT BELT & RETRACTOR.......8O-20
FRONT SEAT BELT BUCKLE............8O-23
FRONT TURN / PARK / SIDE MARKER
LAMP BULB.........................8L-15
FRONT WHEEL SPEED SENSOR..........5-31
FRONT...............................2-1
FUEL DELIVERY.......................14-6
FUEL DOSING PUMP.................24-106
FUEL DRAIN TUBES..................14-10
FUEL FILL DOOR.....................23-48
FUEL FILTER CLOGGED INDICATOR......8J-17
FUEL FILTER........................14-10
FUEL GAUGE........................8J-17
FUEL INJECTOR.......................14-35
FUEL LEVEL SENDING UNIT / SENSOR....14-28
FUEL LINE.........................24-107
FUEL LINES.........................14-11
FUEL PRESSURE SENSOR.............14-39
FUEL PRESSURE SOLENOID............14-40
FUEL PUMP MODULE.................14-18
FUEL PUMP.........................14-13
FUEL QUANTITY CONTROL VALVE.......14-21
FUEL RAIL PRESSURE SENSOR.........14-12
FUEL RAIL..........................14-22
FUEL SYSTEM........................14-1
FUEL TANK.........................14-23
FUEL TEMPERATURE SENSOR..........14-42
FUSE BLOCK #1...................8W-97-2
FUSE BLOCK #2...................8W-97-3
GAP AND FLUSH.....................23-91
GEAR SELECTOR INDICATOR...........8J-18
GEAR...............................19-7
GEARSHIFT CABLE..................21-138
GEAR - PINION / RING.................3-41
GENERATOR DECOUPLER PULLEY.......8F-19
GENERATOR........................8F-18
GLOVE BOX.........................23-58
GLOW PLUG RELAY....................8I-1
GLOW PLUG..........................8I-1
GRILLE............................23-48
HCU (HYDRAULIC CONTROL UNIT).......5-36
HEADLAMP LEVELING MOTOR..........8L-16
HEADLAMP LEVELING SWITCH.........8L-17
HEADLINER.........................23-73
HEADREST..........................23-79
HEATED GLASS.......................8G-1
HEATED MIRRORS....................8G-9
HEATED SEAT ELEMENT...............8G-12
HEATED SEAT RELAY.................8G-12
HEATED SEAT SENSOR................8G-13
HEATED SEATS ......................8G-10
HEATER CORE.......................24-76
HEATER UNIT......................24-110
HEATING & AIR CONDITIONING..........24-1
HIGH BEAM HEADLAMP BULB..........8L-18
HIGH BEAM INDICATOR...............8J-19
HINGE..................23-17, 23-32, 23-51
HOISTING............................0-5
HOLDING CLUTCH B1................21-143
HOLDING CLUTCH B2................21-148
HOLDING CLUTCHES.................21-141
HOOD.............................23-51
HORN SWITCH.......................8H-1
HORN..............................8H-1
HOSES.............................19-14
HUB / BEARING........................2-4
HVAC HOUSING......................24-48
HYDRAULIC / MECHANICAL..............5-5
IGNITION CONTROL....................8I-1
INLET HOSE........................24-111
INPUT CLUTCH K1
...................21-92
INPUT CLUTCH K2
...................21-97
INPUT CLUTCH K3
..................21-102
INPUT CLUTCHES
....................21-90
INPUT SPEED SENSORS
..............21-153
VAINDEX 1
Description Group-Page Description Group-Page Description Group-Page

TABLE OF CONTENTS - Continued
BACKUP LAMP CKT SHORT TO VOLTAGE OR OPEN........................15
BACKUP LAMP SUPPLY CIRCUIT OPEN...................................16
CAN BUS CIRCUIT......................................................17
INCORRECT CAN MESSAGE FROM ABS...................................18
INTERNAL CONTROLLER................................................19
LR WHEEL SPIN CAN MESSAGE NOT VALID...............................20
OVER VOLTAGE........................................................21
RR WHEEL SPIN CAN MESSAGE NOT VALID...............................22
UNDER VOLTAGE......................................................23
TRANSMISSION - NAG1
1-2/4-5 SOLENOID CIRCUIT..............................................24
1-2/4-5 SOLENOID CIRCUIT SHORT TO GROUND...........................24
2-3 SOLENOID CIRCUIT.................................................27
2-3 SOLENOID CIRCUIT SHORT TO GROUND..............................27
3-4 SOLENOID CIRCUIT.................................................30
3-4 SOLENOID CIRCUIT SHORT TO GROUND..............................30
ABS BRAKE MESSAGE..................................................33
ABS CAN MESSAGE INCORRECT.........................................35
ABS CAN MESSAGE MISSING............................................36
ABS LF SENSOR MESSAGE..............................................38
ABS LR SENSOR MESSAGE.............................................40
ABS RF SENSOR MESSAGE.............................................42
ABS RR SENSOR MESSAGE.............................................44
ACCEL PEDAL SENSOR CAN MESSAGE INCORRECT.......................46
CAN BUS CIRCUIT......................................................48
CAN MESSAGE FROM ECM FROM SLA....................................53
CONTROL MODULE TCM IS NOT CODED..................................55
ENGINE CAN MESSAGE INCORRECT.....................................56
ENGINE CAN MESSAGE MISSING........................................58
ENGINE OVERSPEED...................................................60
ENGINE RPM MESSAGE.................................................62
ENGINE TEMP MESSAGE................................................64
ENGINE TORQUE MESSAGE INCORRECT.................................66
ENGINE TORQUE REDUCTION...........................................68
IC CAN MESSAGE INCORRECT..........................................70
IC/ATC CAN MESSAGE MISSING..........................................72
IMPROPER GEAR......................................................74
IMPROPER RATIO......................................................76
INPUT SENSOR MISMATCH..............................................78
INPUT SENSOR OVERSPEED............................................80
INTERNAL CONTROLLER................................................82
INVALID CONTROL MODULE VERSION....................................83
MODULATING PRESSURE SOLENOID CIRCUIT.............................84
N2 INPUT SPEED SENSOR CIRCUIT......................................87
N3 INPUT SPEED SENSOR CIRCUIT......................................91
SENSOR SUPPLY VOLTAGE..............................................95
SHIFT LEVER POSITION INVALID.........................................97
SHIFT PRESSURE SOLENOID CIRCUIT....................................99
SLA CAN MESSAGE INCORRECT........................................102
SOLENOID SUPPLY VOLTAGE...........................................103
SOLENOID SUPPLY/WATCHDOG.........................................105
SYSTEM OVERVOLTAGE...............................................107
ii

TABLE OF CONTENTS - Continued
SYSTEM UNDERVOLTAGE..............................................109
TCC OVER TEMP......................................................111
TCC SOLENOID CIRCUIT...............................................112
TCC STUCK ON.......................................................115
TRANS TEMP SENSOR - P/N SWITCH CIRCUIT............................117
TRANS TEMP SENSOR ERRATIC........................................120
TRANS TEMP SENSOR SHORTED.......................................122
TRANSMISSION SLIPPING..............................................125
VERIFICATION TESTS
VERIFICATION TESTS..................................................127
8.0 COMPONENT LOCATIONS..............................................129
8.1ENGINE CONTROL MODULE.......................................129
8.2TRANSMISSION CONTROL MODULE................................129
8.3TRANSMISSION SOLENOID ASSEMBLY..............................129
9.0 CONNECTOR PINOUTS................................................131
ELECTROHYDRAULIC CONTROL UNIT - BLACK...........................131
SHIFTER ASSEMBLY - BLACK...........................................131
TRANSMISSION CONTROL MODULE C1 - BLACK..........................131
TRANSMISSION CONTROL MODULE C2 - BLACK..........................132
TRANSMISSION RELAY (RELAY BLOCK)..................................133
10.0 SCHEMATIC DIAGRAMS................................................135
11.0 CHARTS AND GRAPHS................................................137
11.15 VOLT SQUARE WAVE ± TYPICAL PATTERN.........................137
11.2TRANSMISSION TEMP SENSOR....................................138
iii

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

3-4 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