Aw55 50 Differences Between Manufacturers Part One
Article No.:
TASC TIP-06-08
Author:
Jeff Parlee
AW55-50 Differences between
Total Pages:
2
Manufacturers - Part One
In the United States, the AW55-50 is used in the:
As with almost all newer transmissions, the
• Saturn Ion and Vue, (AF23-5 in the 4 cylinder
AW55-50 relies on adaptive strategy to adjust
and AF33-5 in the V-6)
the shift feel for each shift. Whenever the
transmission is overhauled or replaced, the
•
Chevrolet Equinox and the Pontiac
valve body is replaced or the transmission
Torrent, (AF33-5)
control module (TCM) is replaced, the shift
•
Nissan Altima, Maxima and Quest,
adapts must be cleared and relearned.
(RE5F22A)
Failure to perform these procedures can result
• Saab 9-3 and 9-5
in shift feel and downshift clunk complaints,
• Volvo C70, S40, S60, S70, S80, S90, V40,
as well as reduced transmission life. Some
V50, V70, XC70 and the XC90
vehicles relearn slowly and need to be
relearned with a dealer equivalent scan tool.
As you can see, there are a lot of these transmis-
You don’t want to damage your fresh overhaul
sions on the street. It is important that you
waiting for the computer to relearn its adapts.
understand what a normal operating condition
is and what is not normal for the vehicle that
The challenge presented by having multiple
you are working on. Not all AW55-50 trans-
manufacturers using the AW55-50 is that
missions have the same operating features. As
you need to be aware of the different operat-
an example, Saturn has eight operating
ing modes and different relearn techniques.
modes or shift strategies. They are normal
Understanding the operating system and pro-
mode, protection mode, cold mode, hot
cedures for each vehicle and knowing what
mode, uphill mode, downhill mode, high
bulletins and updates are available will go a
altitude mode and traffic jam mode. Each
long way toward fixing the car right the first
one of these modes has a different shift strategy.
time and keep you from wasting your time.
The customer is familiar with normal mode
Next month we will cover the adaptives and
and may have noticed cold mode. The other
their relearn procedures along with some
modes don’t show up very often and if noticed
known bulletins you should be aware of. For
they may be seen as a very intermittent problem.
now, let’s have a look at the variety of operating
You may have a customer come in with a
modes. As stated earlier, GM/Saturn strategy
Saturn that has a complaint of 2nd gear starts
augments the normal operating mode with
or seems very sluggish with a lack of power
seven additional modes as outlined below.
from a start. The customer says that this only
GM/Saturn Shift Modes
happens once in awhile. You could spend a
lot of time trying to diagnose this normal
Protection Mode – This mode is like failsafe
condition, if you don’t know that the computer
or limp-in mode in other vehicles. When the
is commanding the shifts in traffic jam mode. protection mode is tripped by a code you will
have 5th gear in drive and intermediate.
Some Volvo models have a Neutral Control
When in manual low you will have 2nd gear.
feature. This is when the computer turns off
Cycling the ignition will give you normal
the C1 clutch when the vehicle comes to a
mode again until the code is set again.
complete stop for more than 2 seconds with
the brake applied. This is a feature that the
Cold Mode – When the engine coolant tem-
customer should never feel, but quite frequent-
perature is less than 122°F, the shifts will
ly you will get a harsh re-engagement and
occur at a higher speed.
sometimes a downshift thud when the C1
Hot Mode – When the transmission oil
Automatic Drive P.O. Box 440
clutch releases. Volvo has software updates to fix
temperature reaches 284°F, the computer
Bellows Falls, VT 05101-0440 USA
this as well as flare 2-3 shifts, harsh down shifts
applies the converter clutch at lower than
800-843-2600 • fax: 802-463-4059
and harsh garage shifts. Most manufacturers
normal speeds and raises the shift points to a
email: info@sonnax.com •
www.sonnax.com
have software upgrades for this transmission.
high speed. When the transmission oil tem-
Check with your local dealer for the latest
perature drops below 270°F, normal mode
©2008 Sonnax Industries, Inc.
upgrades available for your application.
will resume.
Downhill Mode – When the throttle angle is less than 3% and the
Slipping Lock-up – Slipping lock-up mode allows for a smoother
vehicle speed is increasing, the computer will command higher shift
lock-up engagement while reducing vibration and noise. The computer
speeds to provide more engine braking.
maintains a 50 to 200 RPM torque converter clutch slip in this mode.
Uphill Mode – When engine load is high and vehicle speed is
The following conditions must be met for this mode to activate:
decreasing, the computer will command higher shift speeds.
• Gear shifter must be in the D, 4, or 3 position.
High Altitude Mode – When the barometric pressure is less than
• Transmission must be in 3rd, 4th, or 5th gear.
12.76, the computer will command higher shift speeds.
• The transmission input speed must be 1100 RPM or higher and
Traffic Jam Mode – When the vehicle stops and starts with less than
the throttle opening must be 35% or less.
10% throttle angle, the computer commands 2nd gear starts to
increase fuel economy and reduce shift busyness. Normal mode
• Engine coolant must reach a certain temperature.
resumes when the throttle angle is greater than 30% or vehicle speed
• Transmission oil temperature must be at least 40°C (104°F), but
is greater than 18.6 MPH.
not to exceed 120°C (248°F).
Volvo Shift Modes
Note: The friction properties of this transmission fluid are different
from other fluids due to the large amount of converter clutch slip.
Economy Mode – This mode is used by TCM under normal accel-
Failure to use the correct fluid will cause transmission damage
eration. The TCM provides the earliest possible upshifts and lockup
and codes.
for best economy. The TCM adjusts oil pressure to provide smooth
shifts and engagements.
Driving Uphill – To reduce shift business, the TCM may change the
shift pattern slightly when driving uphill.
Sport Mode – The TCM changes from economy to sport mode if
the accelerator pedal is pressed down quickly and the vehicle exceeds
Neutral Control – (This function is not available on all models).
31MPH. In sports mode the shift points are raised to provide the
Neutral control is when the TCM disengages the forward clutch, (C1), at
best performance and down shifting occurs at lower engine RPM.
a stop with the brake applied. This reduces the load on the engine, there-
When the accelerator pedal is moved less quickly, the TCM resumes
fore reducing engine vibration and improving fuel economy. When the
economy mode automatically.
brake is released the forward clutch engages. The following conditions
Extreme Mode – Extreme mode is another way of saying kick-down.
must be met before the neutral control function will be allowed:
The TCM selects the lowest possible gear, for the vehicle speed, when
• Manual shifter must be in D, 4 or 3. Neutral control will not work
the throttle is depressed to the floor.
in winter mode or when Geartronic is selected.
Winter Mode – Winter mode is selected by using the “W” button on the
•Transmission oil temperature must be above 10°C or 50°F.
top panel of the gear selector assembly. A warning lamp in the instrument
• Throttle position must be less than 3%.
cluster illuminates when winter mode has been selected. When winter
• Brake pedal must be depressed.
mode is activated, the transmission will start out in 3rd gear to provide
maximum traction on slippery surfaces. Depending on manual gear
• Vehicle speed must be zero MPH.
selection, the following shift combinations can be obtained.
• Engine speed must be less than 1500 RPM.
• D – The transaxle starts in 3rd gear, automatically shifting between
• There is a 2 second delay once the vehicle has stopped in the D
3rd, 4th, and 5th gears.
position and a 5 second delay when shifted from N to D.
• 4 – The transaxle starts in 3rd gear and automatically shifts to 4th
Shifting using Geartronic
gear earlier than economy mode in D range. 5th gear is locked out.
When the shifter is moved to the Geartronic position, the transmis-
• 3 – The transaxle starts in 3rd gear with no up shifts or down shifts.
sion remains in the hydraulic “D” position. When the shifter is
• L – The transaxle starts in 2nd gear with no up shifts or down shifts.
moved to the + or – positions, the gear selector module sends a sig-
At wide-open throttle in winter mode, the transaxle uses all gears for
nal to the TCM to shift the transmission up or down. The driver
maximum performance.
information module changes the symbol on the instrument cluster
from D to the gear that has been selected. A signal is sent to the gear
Catalytic Converter Start – This function helps the engine to reach
selector module to light the M and turn off the other LED’s on the
operating temperature by preventing converter lockup and delaying the
shifter console. The TCM determines if the shift can be carried out
1-2 and 2-3 upshifts when the engine is cold. This is a normal function.
and activates the appropriate solenoids. The TCM will override the
Temperature Controlled Lock-up – If the transmission temperature
driver’s command under certain circumstances. The following
rises excessively as a result of a heavy load with high ambient temperature
applies during Geartronic shifting:
conditions, the torque converter clutch is applied to reduce heat gen-
• Only 1st, 2nd, or 3rd gears can be selected from a stop. The trans-
erated by the torque converter. If the temperature drops below 20°C,
mission will not up shift into 4th gear until a speed of at least
(68°F), lock-up will be inhibited.
Article No.: TASC TIP-06-08 Author: Jeff Parlee
©2008 Sonnax Industries Inc.
Page 2
19MPH has been reached. The transmission will not up shift into
the transmission fluid temperature exceeds 135°C. This program
5th until a speed of at least 25MPH has been reached.
forces the up shifts at an even higher speed and converter lock-up
• Automatic down shifting occurs below certain speeds if driver forgets
happens more often than in Temperature program 1. Lock-up is
to manually down shift transmission. Manual up shifting is
commanded on with no slippage during this program. Temperature
required after automatic down shifting has occurred.
program 2 will deactivate when the transmission fluid temperature
drops below 127C and returns to Temperature program 1.
• Kick-down is not available in Geartronic mode.
If the transmission fluid temperature rises above 155°C for more
• The TCM will not allow the transmission to be manually down
than 2 seconds, code P0218 is set, the temperature is recorded, the
shifted if the engine speed would exceed 6000 RPM.
“CHECK GEARBOX” light does NOT light, and the TCM sends a
• If the transmission temperature gets too high, the TCM will select
Bus message of “TRANSMISSION OVERHEATING” which is
the correct gear so that lockup can be used.
shown in the PID display. Engine torque is reduced to a maximum
• Torque converter lock-up is only possible in 3rd, 4th, and 5th.
of 200Nm to protect the transaxle.
Special Gear Change Program - A special gear change program is
Nissan Shift Modes
automatically activated if a high load is detected. The up shifts and
Downslope Mode – The TCM detects downhill driving when the
down shifts will occur at a higher engine speed to keep the transmis-
vehicle speed increases with a closed throttle. During Downslope
sion fluid from overheating. Examples of when this program would
mode the TCM changes the shift points for more engine braking.
engage are: driving up long hills and trailer towing. The special gear
Upslope Mode – The TCM detects uphill driving when the engine
change program will not initiate above 150 km/h.
load is high and the vehicle speed decreases. Upslope mode raises
DPS Program - Differential protection system or DPS reduces
normal shift points to avoid busy shifting.
engine torque during extreme wheel spin. DPS will only activate
Hot Mode Control – When the transaxle temperature gets too high,
below 80km/h. 150Nm is the maximum engine torque allowed dur-
(no specification is given by Nissan), the TCM changes the shift
ing DPS activation.
points to reduce the transaxle temperature.
Reverse Inhibit Program - There is a reverse inhibit feature that will
Manual Mode – When the manual shift lever is moved to the man-
turn on the S1 solenoid, which releases the B3 brake, if the TCM
ual shift position, the driver can manually up shift and down shift the
detects that the vehicle is moving at 7 km/h, (4.3 mph), or faster.
transaxle. The TCM will automatically up shift the transaxle if the
Reading about all these modes makes it easy to see many possible
engine exceeds a specified RPM. The TCM will automatically down
intended or normal functions that could be mistaken for a functional
shift the transaxle if the vehicle speed falls below a specified value to
problem. You will need to consider these modes carefully during your
avoid transaxle damage. The TCM will control converter clutch
diagnosis, just as you will need to carefully work with relearn strategies
operation at all times.
when you complete a repair. We will cover those next month.
Saab Shift Programs
Manual Shifting Program - Manual shifting can be accomplished
Jeff Parlee is Director of Product Support at Valve Body
by moving the manual shift lever to the “M” position. The driver can
Xpress and a member of the Sonnax TASC Force. (Technical
then control the up shifts and down shifts using the + and – buttons
Automotive Specialties Committee), a group of recognized
on the steering wheel. The TCM will override the manual controls if
industry technical specialists, transmission rebuilders and
the engine RPM’s get too high and the shift has not been commanded
Sonnax Industries Inc. technicians.
by the driver, or the driver forgets to down shift when the vehicle
speed drops below the threshold for the selected gear. The TCM will
not allow the driver to down shift the vehicle manually until the
vehicle speed drops below a predetermined point for the particular
gear. The driver can start from a stop in 1st, 2nd or 3rd only. The
manual feature can even be used when cruise control is on.
Temperature Program 1 - Temperature program 1 is activated when the
transmission fluid temperature exceeds 125°C. Lock-up is activated
in 3rd and 4th with no converter slip and the shifts are at a higher
speed to cool the transmission fluid. When the transmission fluid
temperature drops below 120°C the Temperature program 1 deactivates.
Temperature program 1 will not activate when the TCM is in limp home.
Temperature Program 2 - Temperature program 2 is activated when
Article No.: TASC TIP-06-08 Author: Jeff Parlee
©2008 Sonnax Industries Inc.
Page 3
