Chrysler 300M 2002 Service Manual page 2807

GENERAL INFORMATION
Transmission Effects: If the 2/4 pressure
switch is identified as closed in P or N, the code will
immediately be set and normal operation will be
allowed for that given key start. If the problem is
identified for 3 successive key starts, the transmis-
sion will go into Limp-in mode.
If the 2/4 pressure switch is identified as being
closed in 1st or 3rd gear and was not identified as
being closed in P or N, then 2nd gear or 4th gear
will be substituted for 1st or 3rd gear depending on
throttle angle and vehicle speed. A short period of
time after the gear substitution, the transmission
will return to normal operating mode. If the trans-
mission is shifted back into 1st or 3rd gear through
normal operation, and the 2/4 pressure switch
remains closed, 2nd or 4th gear will be substituted
briefly and then resume normal operation. If four
gear substitutions occur in a given key start, the
transmission will go into Limp-in mode.
If the 2/4 pressure switch is open (indicating no
2/4 clutch pressure) in 2nd or 4th gear, the Trans-
mission Control System sets code P0846(22) and
continues with normal operation. The transmis-
sion will only go into Limp-in mode if a code
P0706(28) is also present. If no 2/4 clutch pressure
is present a gear ratio code P0732(52) or P0734(54)
will be set and cause the Limp-in condition.
Possible causes:
> If code P0944(35) is present, ignore code
P0846(22) and perform code P0944 diagnostic
procedures
> 2/4 pressure switch sense circuit open or
shorted to ground between TCM and solenoid
pack
> 2/4 pressure switch sense circuit shorted to
battery
> Solenoid pack
> Transmission overheated - Excessive regula-
tor valve leakage in valve body causing high
line pressure which results in 2/4 solenoid
blow-off in 1st or 3rd gear. May require new
valve body if it happens only when hot.
> Loose valve body bolts
> Plugged filter - internal transmission or
torque converter failure
> PCM
Name of code: P0841(24) - LR Pressure Switch
Sense Circuit
When monitored: Whenever the engine is run-
ning.
Set condition: This code is set if the LR pressure
switch is either open or closed at the wrong time in
a given gear.
Theory of operation: The Transmission system
uses three pressure switches to monitor the fluid
pressure in the LR, 2/4, and OD elements. The
pressure switches are continuously monitored for
the correct states in each gear.
Transmission Effects: If a set condition is iden-
tified, 1st gear and torque converter lock-up
(EMCC) will be inhibited. The vehicle will launch
in 2nd gear and shift normally through the gears
without allowing EMCC. If during the same key
start, the set condition is no longer valid, the
transmission will return to normal operation (1st
and EMCC available). Limp-in will not occur un-
less code P0841(24) is accompanied by a code
P0706(28) and the MIL will illuminate after 5
minutes of substituted operation.
Possible causes:
> If code P0944(35) is present, ignore code
P0841(24) and perform code P0944(35) diag-
nostic procedures
> LR pressure switch sense circuit open or
shorted to ground between TCM and solenoid
pack
> LR pressure switch sense circuit shorted to
battery
> Solenoid Pressure Switch assembly
> Valve body - solenoid switch valve stuck in
LU position. May be accompanied by a code
P1775(37)
> Loose valve body bolts
> Plugged filter - internal transmission or
torque converter failure
> PCM
Name of code: P0706(28) - Check Shifter Signal
When monitored: Continuously with the key on.
Set condition: 3 occurrences in one key start of an
invalid PRNDL code which lasts for more than 0.1
second.
Theory of operation: The C1 through C4 (T1, T3,
T41, and T42) sense circuits communicate the shift
lever position to the PCM. Each circuit is termi-
nated at the transmission with a switch. Each
switch can be either open or closed, depending on
the shift lever position. The PCM can decode this
information and determine the shift lever position.
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