The TCM also tests the 2/4 and OD pressure
switches when they are normally off (OD and 2/4 are
tested in 1st gear, OD in 2nd gear, and 2/4 in 2nd
gear). The test simply verifies that they are opera-
tional, by looking for a closed state when the corre-
sponding element is applied. Immediately after a
shift into 1st, 2nd, or 3rd gear with the engine speed
above 1000 rpm, the TCM momentarily turns on ele-
ment pressure to the 2/4 and/or OD clutch circuits to
identify that the appropriate switch has closed. If it
doesn’t close, it is tested again. If the switch fails to
close the second time, the appropriate Diagnostic
Trouble Code (DTC) will set.
TRANSMISSION RANGE SENSOR
DESCRIPTION
The Transmission Range Sensor (TRS) is mounted
to the top of the valve body inside the transaxle and
can only be serviced by removing the valve body. The
electrical connector extends through the transaxle
case (Fig. 18).
The Transmission Range Sensor (TRS) has four
switch contacts that monitor shift lever position and
send the information to the TCM.
The TRS also has an integrated temperature sen-
sor (thermistor) that communicates transaxle tem-
perature to the TCM and PCM (Fig. 19).
OPERATION
The Transmission Range Sensor (TRS) (Fig. 18)
communicates shift lever position (SLP) to the TCM
as a combination of open and closed switches. Each
shift lever position has an assigned combination of
switch states (open/closed) that the TCM receives
from four sense circuits. The TCM interprets this
information and determines the appropriate tran-
saxle gear position and shift schedule.
Since there are four switches, there are 16 possible
combinations of open and closed switches (codes).
Seven of these codes are related to gear position and
three are recognized as “between gear” codes. This
results in six codes which should never occur. These
are called “invalid” codes. An invalid code will result
in a DTC, and the TCM will then determine the shift
lever position based on pressure switch data. This
PRESSURE SWITCH STATES
GEAR L/R 2/4 OD
ROPOPOP
P/N CL OP OP
1st CL OP OP
2nd OP CL OP
DOPOPCL
OD OP CL CL
OP = OPEN
CL = CLOSED
Fig. 18 Transmission Range Sensor (TRS) Location
1 – SOLENOID/PRESSURE SWITCH ASSEMBLY
2 – TRS
3 – TRANSFER PLATE
4 – SEPARATOR PLATE
5 – VALVE BODY
Fig. 19 Transmission Temperature Sensor
1 – TRANSMISSION RANGE SENSOR
2 – TEMPERATURE SENSOR
LH 42LE TRANSAXLE 21 - 15
DESCRIPTION AND OPERATION (Continued)
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