Saturn Transmission. Manual - part 2

COMMAND LINE PRESSURE

"DESIRED"

PRESSURE GAUGE READINGS

"ACTUAL"

Figure 16

DIAGNOSTIC INFORMATION:

VISUAL/PHYSICAL UNDERHOOD INSPECTION
A careful visual and physical underhood inspection must
be  performed  as  part  of  any  diagnostic  procedure  or  in
finding the cause of a failure. This can often lead to fixing a
problem without further steps. Inspect wiring, fluid, cables
and  linkage.  Inspect  all  the  wires  in  the  engine
compartment  for  proper  connections,  burned  or  chafed
spots, pinched wires, or contact with sharp edges or hot
exhaust manifolds. This visual/physical inspection is very
important. It must be done carefully and thoroughly.

DIAGNOSTIC TROUBLE CODES
Diagnostic trouble codes or information flags are two digit
numbers that can range from 11 to 99. When a malfunction
(MALF) is detected by the PCM, a diagnostic trouble code
or information flag is set and the
malfunction indicator lamp (MIL) telltale lamp may be
illuminated.

Diagnostic Trouble Code (DTC): Suspected failure
detected in the engine or transaxle will turn on MIL lamp
when failure is present.

Information flag: A diagnostic aid used when a minor
malfunction or intermittent problem occurs. It does not
necessarily indicate a failure.

MALFUNCTION INDICATOR LAMP
This telltale lamp (SERVICE ENGINE SOON telltale
lamp) is in the instrument cluster and has the following
functions:

It informs the driver that a problem has occurred and that
the vehicle should be taken for service as soon as
reasonably possible.

It displays diagnostic trouble codes and/or information
flags stored by the PCM which help the technician
diagnose system problems.

It indicates "Open Loop" or "Closed Loop" engine
operation.

As a bulb and system check, the lamp will come on with
the key On and the engine not running. When the engine is
started, the lamp will turn off. If the lamp remains on, the
self-diagnostic  system  has  detected  a  problem.  If  the
problem  goes  away,  the  lamp  will  go  out  in  most  cases
after 10 seconds, but a diagnostic trouble code will remain
stored in the PCM.
When the lamp remains on while the engine is running, or
when  a  malfunction  is  suspected  due  to  a  driveability
problem,  code  retrieval  must  be  performed.  All  engine
codes,  diagnosis  and  repairs  should  be  dealt  with  first
before attempting to move onto the transaxle codes and
information flags.

AUTOMATIC TRANSMISSION SERVICE GROUP

Technical Service Information

TRANSAXLE SHIFT TO D2 TELLTALE
LAMP (1991-1992 VEHICLES)

When a transaxle malfunction is detected, the malfunction
indicator  lamp  (MIL)  telltale  lamp  may  illuminate.  The
telltale  lamp  will  illuminate  for  all  diagnostic  trouble
codes, but will not illuminate for information flags. A DTC
12  will  flash  followed  by  any  engine  diagnostic  trouble
codes that may be present,   then a DTC 11 will follow.
After DTC 11 is flashed three times, the SHIFT TO D2
telltale lamp will flash stored diagnostic trouble codes. If
an information flag in the transaxle is stored along with
diagnostic trouble codes, they will also be flashed at the
same  time.  If  only  information  flags  are  stored  and  a
diagnostic check is completed, DTC 12 will flash followed
by any engine diagnostic trouble codes, no DTC 11 will be
flashed, but the SHIFT TO D2 telltale lamp will begin to
flash  transaxle  flags. Automatic  transaxle  flags  will  not
turn on the MIL lamp and are used as diagnostic aids. If a
faulty Shift to D2 telltale bulb or circuit is suspected, it can
be  checked  with  some  scanners  by  selecting  the  TCM
menu. DTC 26 may also be logged if the Shift to D2 lamp
circuit has a fault.

LOW COOLANT/HOT LAMP
(1993 AND 1994 VEHICLES)

For 1993 and 1994, the SHIFT TO D2 lamp has been
eliminated. The low coolant hot lamp will flash diagnostic
trouble codes or information flags the same way as
described above under the heading TRANSAXLE SHIFT
TO D2 TELLTALE LAMP.

INTERMITTENT MALFUNCTION
INDICATOR LAMP (MIL) TELLTALE LAMP

In the case of an intermittent problem, the MIL telltale
lamp will illuminate for 10 seconds and then will go out.
However, the corresponding diagnostic trouble code and
any information flags set by the problem will be stored in
the memory of the PCM until removed.

READING DIAGNOSTIC TROUBLE CODES

The provision for communicating with the PCM is the data
link  connector  (DLC)  which  is  located  under  the
instrument panel (See Figure 17). The diagnostic trouble
code(s) or information flag(s) stored in the PCM's memory
can be read either through a hand-held diagnostic scanner
plugged  in  the  data  link  connector  or  by  grounding  the
diagnostic  terminal  in  the  data  link  connector.  Once
terminal  B  (The  Diagnostic  Terminal)  is  connected  to
terminal A (The Internal PCM Ground)

Data Link Connector

Figure 17

as shown in Figure 17 above, the ignition switch must be
moved to the ON position, with the engine not running. At
this point, the MIL telltale lamp should flash a Diagnostic
Trouble Code (DTC) 12 three times consecutively
(Remember, the MIL telltale lamp is for PCM (EC)
diagnostic trouble codes or SHIFT TO D2 lamp on 1991
and 1992 vehicles. The LOW COOLANT/HOT lamp is
used on 1993 and 1994 vehicles for PCM (TC) diagnostic
trouble codes)

The  flash  sequence  would  be  as  follows:  Flash,  pause,
flash-flash,  long  pause,  flash,  pause,  flash-flash,  long
pause, flash, pause, flash-flash. DTC 12 indicates that the
PCM's diagnostic system is operating. If DTC 12 is not
indicated,  a  problem  is  present  within  the  diagnostic
system itself.
After  the  output  of  DTC  12,  the  MIL  telltale  lamp  will
indicate any engine diagnostic trouble code three times if
any are present, or it will simply continue to output DTC
12.  If  more  than  one  diagnostic  trouble  code  has  been
stored in the PCM's memory, the diagnostic trouble codes
will be displayed from the lowest to the highest, with the
exception of DTC 11 which indicates transaxle diagnostic
trouble codes.
DTC 11 will always flash last, followed by the Shift to D2
telltale  lamp  or  the  low  coolant/hot  telltale  lamp  which
will  flash  transaxle  diagnostic  trouble  codes.  Each
diagnostic trouble code will be displayed three times.

CLEARING DIAGNOSTIC TROUBLE CODES

When a diagnostic trouble code and/or information flag is
set, the PCM stores it in two tables: The General
Information and Malfunction (MALF) History. When

AUTOMATIC TRANSMISSION SERVICE GROUP

Technical Service Information

CLEARING CODES CONTINUED:
clearing  diagnostic  trouble  codes  or  information  flags
from General Information WITHOUT a scan tool, you will
need  to  have  the  ignition  ON  and  ground  the  data  link
terminals A to B three times within five seconds. General
Information  can  also  be  cleared  with  50  ignition  ON
cycles. Malfunction history can be cleared ONLY with a
Scan tool.

NOTE:

Disconnecting power to the PCM has no effect on

stored diagnostic trouble codes or information flags in
Malfunction history, but may clear diagnostic trouble
codes and/or information flags in General Information.

FIELD SERVICE MODE

If  the  diagnostic  terminal  is  grounded  with  the  engine
running, the system will enter the Field Service Mode. In
this mode, the MIL telltale lamp will indicate whether the
system is in open loop or closed loop.
In open loop the MIL telltale lamp flashes two and one-half
times per second.
In closed loop, the lamp flashes once per second. Also, in
closed loop, the telltale lamp will stay off most of the time
if the system is running lean. It will stay on most of the time
if the system is running rich.
While  the  system  is  in  the  Field  Service  Mode  and  the
closed  loop  timer  is  bypassed,  new  diagnostic  trouble
codes cannot be stored, but information flags can be stored
in the PCM.

PCM LEARNING ABILITY

The PCM/EC has a "learning" ability which allows it to
make corrections for minor variations in the fuel system to
improve  driveability.  If  the  battery  is  disconnected,  the
learning process resets and begins again. A change may be
noted in the vehicle's performance. To "teach" the vehicle,
make sure that the engine is at operating temperature. The
vehicle  should  be  driven  at  part  throttle,  with  moderate
acceleration and idle conditions until normal performance
returns. To  relearn  idle  the  engine  should  be  idled  in  D
(Drive) with the vehicle at operating temperature until idle
stabilizes.
The TC portion of the PCM also has a learning ability to
achieve smooth shifts. If the battery is disconnected, the
TCM will loose the fine tuning of shift points, which has
been learned while driving the vehicle. Disconnecting the
battery will not reset the TCM adaptive parameters. The
adaptives  can  only  be  reset  using  the  service  stall
system (SSS). To relearn the shifts, the vehicle should
be driven so that each shift is achieved at least twice.

RESETTING ADAPTIVE PARAMETERS

Because the PCM/TC has the ability to adapt to various
transaxle conditions, it is necessary to reset the adaptive
parameters after certain repairs have been performed. The
adaptives can be reset using the service stall system (SSS).
The adaptives should only be reset after the following
repairs have been made:

Replacing a transaxle.
Replacing a line pressure actuator.
Transaxle overhaul when new clutch plates are
installed.
Replacing a valvebody.
Replacing the PCM for a transaxle related failure.

After performing a repair, the vehicle must be driven to
allow the adaptives to learn new shift times and pressures
before returning the vehicle to a customer.
Refer to Learn-in procedure below.

LEARN-IN PROCEDURE

If one of the repairs mentioned has been performed, then
the adaptives should be reset using the SSS. Also, the
vehicle must be driven, preferably on a highway,
according to the following steps. By following these steps,
the adaptives will be properly learned prior to returning the
vehicle to the customer.

1. Place shift mode switch in the normal mode
position.
2. Warm up transaxle (oil temp. above 45°C [113°F]).
3. Perform 10 sets of upshift (1-2, 2-3, 3-4) at 30%
throttle:

DOHC (LLO) Engine

1. While coasting at 56 km/h (35 mph) slowly accelerate
to half throttle to achieve a 4-3 downshift.
2. With selector in D3 while coasting at 32 km/h (20
mph) slowly accelerate to 75% throttle to achieve a
3-2 downshift.
Repeat both procedures five times.

SOHC (LKO) Engine

1. While coasting at 64 km/h (40 mph) slowly accelerate
to half throttle to achieve a 4-3 downshift.
2. With selector in D3 while coasting at 48 km/h (30
mph) slowly accelerate to one half throttle to achieve
a 3-2 downshift.
Repeat both procedures five times.

AUTOMATIC TRANSMISSION SERVICE GROUP

Technical Service Information

The following conditions cause adaptives to be disabled.
• Oil temperature disable (trans oil temperature less than
28°C [82°F] or trans oil temperature greater than
140°C [284°F]).
• TP sensor movement during shift. Movement greater
than 8% at beginning of shift.
• Non-adaptable shift.
a. Downshift to first gear.
b. Garage shifts.
• Serial data loss (active DTC 51 - DTC does not have to
be set).
• Low ignition voltage (ignition voltage less than 11.5
volts).

SHIFT TO D2 LAMP (1991-1992)

The Shift to D2 indicator lamp is lit when any of the
following conditions exist:
• Any time serial communications to TCM are being
run.
• Scan tool connected or the diagnostic terminal is
grounded.
• The engine running and the system is failed at low line.
• The engine is running and all gears above 1st (2nd, 3rd
and 4th) are lost in Drive.
• The engine is running and the master enable relay is
turned off for any reason other than hot conditions and
the vehicle speed is less than 25 KPH (15 MPH).These
include:
a. High ignition voltage.
b. Low ignition voltage.
c. Master relay failed open.

d. Master Relay Shorted

Across Coil.

e. Serial communications failure.
• The engine is running and 3rd or 4th gears are stuck on
and the vehicle speed is less than

25 KPH (15 MPH).

• The engine is running and

TCC is stuck on and first

gear is unattainable with turbine speed less than 700
RPM.
• The ECM will light the Shift - to - D2 light when it
loses communications with the TCM (ECM Code
82).

TCC PARAMETERS

Engine  temperature  above  50°C  (122°F).  Transaxle
temperature above a given value in relation to intake air
temperature (IAT) sensor valve.
  a. TCC on if IAT value is less than -14°C (7°F)and
  transaxle temperature is greater than +20°C (68°F).
  b. TCC on if IAT value is greater than 10°C (50°F) and
  transaxle temperature is greater than +10°C (50°F).
  c. TCC on for the IAT range between -14°C (7°F) and
  +10°C (50°F) uses a calculated transaxle oil
temperature required to allow TCC.
• Above 20% No throttle, TCC on in 2nd gear.
• Below 20% No throttle, TCC on in 3rd gear.
• Low engine speed downshift (i.e., light throttle or
  steady) throttle with load increase.
• Low end of 3rd gear speed range, brake on = TCC off.
• TCC off on all coast downshifts.
• Fast decel; i.e., brake lock on ice = TCC off, gear =
neutral.
• On 1993 vehicles the TCC may be commanded on at
high throttle openings in 1st gear.

AUTOMATIC TRANSAXLE ADAPTIVE
DISABLES

13
13
14
14
15
16
18
18
21

NUMBER

1991-1995 CODE DESCRIPTION

CODE/FLAG

Line Pressure High (1992-1994 Vehicles)*
Line Pressure High (1991 Vehicles)*
Line pressure Low (1993-1994 Vehicles)*
Line Pressure Low (1991-1992 Vehicles)*
Hot Lamp Illuminated
No 1st Gear
No Gears Available (1993-1994 Vehicles)*
No Gears Available (1991-1992 Vehicles)*
2nd Gear Stuck On

Code

Flag

Code

Flag
Flag

Code
Code

Flag

Code

Figure 18

* Diagnostic Procedure is the same for both Codes and Flags

AUTOMATIC TRANSMISSION SERVICE GROUP

Technical Service Information

Note: Refer to page 105 for 1996 and Up Trouble Codes

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