3. EGR Monitor
The EGR monitor now runs in a closed throttle
decel or at idle on a warm vehicle. However, it is
necessary to maintain the TPS, Map and RPM
ranges to allow the monitor to complete itself. For
the monitor run conditions, select the EGR PRE-
TEST in the DRB III
t, OBD II Monitors Menu.
4. O2 Sensor Heater Monitor
This monitor is now continuously running once
the heaters are energized. Pass information will be
processed at power down. For the monitor run
conditions, select the O2S HEATER MON PRE-
TEST in the DRB III
t, OBD II Monitors Menu.
3.2.3
TRANSMISSION CONTROL
The 42RLE electronic Transmission has a fully
adaptive control system. The system performs it’s
functions based on continuous real-time sensor
feedback information. The control system automat-
ically adapts to changes in engine performance and
friction element variations to provide consistent
shift quality. The control system ensures that clutch
operation during upshifting and downshifting is
more responsive without increased harshness. The
Powertrain Control Module (PCM) continuously
checks for electrical problems, mechanical prob-
lems, and some hydraulic problems. When a prob-
lem is sensed, the PCM stores a diagnostic trouble
code. Some of these codes cause the Transmission to
go into Limp-in mode. While in this mode, electrical
power is taken away from the Transmission via the
PCM, de-energizing the transmission control relay,
and taking power from the solenoid pack. When this
happens, the only Transmission mechanical func-
tions are:
Park and Neutral
Reverse
Second Gear
No upshifts or downshifts are possible. The posi-
tion of the manual valve alone allows the three
ranges that are available. Although vehicle perfor-
mance is seriously degraded while in this mode, it
allows the owner to drive the vehicle in for service.
Once the DRBIII
t is in the Transmission portion
of the diagnostic program, it constantly monitors
the transmission to see if the system is in Limp-in
mode. If the Transmission is in Limp-in mode, the
DRBIII
t will flash the red LED.
When a problem is sensed, the PCM stores a
diagnostic trouble code (DTC). Some of these codes
cause the transmission to go into
9limp-in9 or 9de-
fault
9 mode.
Once the DRBIII is in the
9Transmission9 portion
of the diagnostic program, it constantly monitors
the PCM to see if the system is in limp-in mode. If
the transmission is in limp-in mode, the DRBIII
t
will flash the red LED.
3.2.3.1
TRANSMISSION OPERATION AND
SHIFT SCHEDULING AT VARIOUS
OIL TEMPERATURES
The transmission covered in this manual has
unique shift schedules depending on the tempera-
ture of the transmission oil. The shift schedule is
modified to extend the life of the transmission while
operating under extreme conditions.
The oil temperature is measured with a Temper-
ature Sensor on the 42RLE transmission. The Tem-
perature Sensor is an integral component of the
Transmission Range Sensor (TRS). If the Tempera-
ture Sensor is faulty, the transmission will default
to a calculated oil temperature. Oil temperature
will then be calculated through a complex heat
transfer equation using engine coolant tempera-
ture, battery/ambient temperature, and engine off
time from the Body Control Module (BCM). These
inputs are received from the PCI bus periodically
and used to initialize the oil temperature at start
up. Once the engine is started, the PCM updates
the transmission oil temperature based on torque
converter slip speed, vehicle speed, gear, and engine
coolant temperature to determine an estimated oil
temperature during vehicle operation. Vehicles us-
ing calculated oil temperature track oil tempera-
ture reasonably accurate during normal operation.
However, if a transmission is overfilled, a transmis-
sion oil cooler becomes restricted, or if a customer
drives aggressively in low gear, the calculated oil
temperature will be inaccurate. Consequently the
shift schedule selected may be inappropriate for the
current conditions. The key highlights of the vari-
ous shift schedules are as follows:
Extreme Cold: Oil temperature at start up below
26.6°C (-16 °F)
> Goes to Cold schedule above -24°C (-12°F) oil
temperature
> Park, Reverse, Neutral and 2nd gear only (pre-
vents shifting which may fail a clutch with fre-
quent shifts)
Cold: Oil temperature at start up above -24°C
(-12°F) and below 2.2°C (36°F)
> Goes to Warm schedule above 4.4°C (40°F) oil
temperature
> Delayed 2-3 upshift approximately 35-50 Km/h
(22 - 31 MPH)
> Delayed 3-4 upshift 72-85 Km/h (45-53 MPH)
> Early 4-3 coastdown shift approximately 48
Km/h (30 MPH)
> Early 3-2 coastdown shift approximately 27
Km/h (17 MPH) ?
5
GENERAL INFORMATION