Chrysler PT Cruiser 2001 Service Manual Supplement page 2057

PT
TRANSMISSION CONTROL MODULE (Continued)
Gear ratios can be determined by using the DRB
Scan Tool and reading the Input/Output Speed Sen-
sor values in the "Monitors" display. Gear ratio can
be obtained by dividing the Input Speed Sensor value
by the Output Speed Sensor value.
For example, if the input shaft is rotating at 1000
rpm and the output shaft is rotating at 500 rpm,
then the TCM can determine that the gear ratio is
2:1. In direct drive (3rd gear), the gear ratio changes
to 1:1. The gear ratio changes as clutches are applied
and released. By monitoring the length of time it
takes for the gear ratio to change following a shift
request, the TCM can determine the volume of fluid
used to apply or release a friction element.
Clutch
L/R
2/4
OD
UD
SHIFT SCHEDULES
As mentioned earlier, the TCM has programming
that allows it to select a variety of shift schedules.
Shift schedule selection is dependent on the follow-
ing:
• Shift lever position
• Throttle position
2001 PT CRUISER
CLUTCH VOLUMES
When Updated
Shift Sequence Oil Temperature
2-1 or 3-1 coast
downshift
1-2 shift
2-3 shift
4-3 or 4-2 shift
ELECTRONIC CONTROL MODULES
The volume of transmission fluid needed to apply
the friction elements are continuously updated for
adaptive controls. As friction material wears, the vol-
ume of fluid need to apply the element increases.
Certain mechanical problems within the clutch
assemblies (broken return springs, out of position
snap rings, excessive clutch pack clearance, improper
assembly, etc.) can cause inadequate or out-of-range
clutch volumes. Also, defective Input/Output Speed
Sensors and wiring can cause these conditions. The
following chart identifies the appropriate clutch vol-
umes and when they are monitored/updated:
Throttle Angle
> 70° < 5°
5 - 54°
> 110°
> 5°
• Engine load
• Fluid temperature
• Software level
As driving conditions change, the TCM appropri-
ately adjusts the shift schedule. Refer to the follow-
ing chart to determine the appropriate operation
expected, depending on driving conditions.
8E - 5
Proper Clutch
Volume
35 to 83
20 to 77
48 to 150
24 to 70