Chrysler PT Cruiser 2001 Service Manual Supplement page 2755

> Solenoid pack defective>
> Transmission overheated - Excessive regulator
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
> TCM
Name of code: P-1784(24) — L-R Pressure Switch
Circuit
When monitored: Whenever the engine is run-
ning.
Set condition: This code is set if the L-R 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 L-R, 2-4, and OD elements. The
pressure switches are continuously monitored for
the correct states in each gear as shown below.
Normal Pressure Switch States
Gear L-R
R OP
N CL
1st CL
2nd OP
3rd OP
4th OP
OP = switch is open
CL = switch is closed
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start, the set condition is no longer valid, the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). A relay open limp-in will not
occur unless code P-1784(24) is accompanied by a
code P-0705(28).
Possible causes:
> If code P-1791(35) is present, ignore code
P-1784(24) and perform code P-1791 diagnostic
procedures
> L-R pressure switch sense circuit open or shorted
to ground between TCM and solenoid pack
> L-R pressure switch sense circuit shorted to
battery
> Solenoid pack
> Valve body- solenoid switch valve stuck in LU
position. (May be accompanied by a code 37)
> Loose valve body bolts
2-4 OD
OP OP
OP OP
OP OP
CL OP
OP CL
CL CL
7
GENERAL INFORMATION
> Plugged filter - internal transmission or torque
converter failure
> TCM
Name of code: P-0705(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 T1, T3, T41, and T42
sense circuits communicate the shift lever position
to the TCM. Each circuit is terminated at the
transmission with a switch. Each switch can be
either open or closed, depending on the shift lever
position. The TCM can decode this information and
determine the shift lever position. Each shift lever
position has a certain combination of switches
which will be open and closed, this is called a
PRNDL code. There are 4 switches, therefore: there
are many possible combinations of open and closed
switches (codes). However, there are only 9 valid
codes (8 for Autostick), one for each gear position
and three recognized between gear codes. The re-
mainder of the codes should never occur, these are
called invalid codes. The following chart shows the
normal switch states for each shift lever position.
TRS Park T1 Rev T2
T1 (C4) OP OP OP CL
T3 (C3) CL CL OP OP
T41 (C1) CL OP OP
T42 (C2) CL CL CL
Transmission Effects: and possible causes:
Scenario 1) - All PRNDL lights stay illuminated
indefinitely in Park following a Key start.
> Wrong Part Number TCM for application
> TRS connector not plugged in
> T1, T3, T41, or T42 circuits are either open,
shorted to ground, or shorted to 12 volts.
> PCI bus failure (Open or shorted resulting in no
communication to BCM or Cluster)
> TRS
> TCM
> BCM
Scenario 2) - ''P'' is indicated following a key start
but all PRNDL lights illuminate in ''N'' following a
shift from ''R'' to ''N''. If PRNDL lights illuminate in
''N'' and shifter is moved directly into ''3'' or ''L''
position without pausing in ''OD'', then the ''OD''
position shift schedule and electronic display will
indicate ''OD'' until the shifter is shifted into the
''OD'' position and held for at least 3 seconds.
> Worn Manual Lever (Rooster Comb). Check for
heavy wearing by TRS switch contacts
N T2 OD T3 3/AS T3
CL CL CL CL OP CL CL
OP OP OP CL CL CL CL
OP CL OP OP OP OP OP OP
CL CL CL OP OP OP OP CL
L