PT Cruiser L4-2.4L Turbo VIN G (2004)
Fig. 8 Example Of CVI Calculation
By comparing the two inputs, the PCM can determine transaxle gear ratio. This is important to the CVI calculation because the PCM determines CVIs
by monitoring how long it takes for a gear change to occur.
Gear ratios can be determined by using the DRBIII Scan Tool and reading the Input/Output Speed Sensor 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 PCM 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 PCM can determine the volume of fluid used to apply or release a friction element.
The volume of transmission fluid needed to apply the friction elements are continuously updated for adaptive controls. As friction material wears, the
volume 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 volumes and when they are monitored/updated:
TRANSMISSION SHIFT SCHEDULES
