Chrysler 300M 2002 Service Manual page 2805

GENERAL INFORMATION
ized to known constants or previously learned
values from EEPROM (Electronic Erasable Pro-
grammable Read Only Memory). This results in
the reinitialization of some parameters.
Transmission Effects: Loss of trouble code data.
Immediate Limp-in mode if power is lost while
operating the vehicle. Normal operation is re-
sumed if the power is restored during the same key
start.
Possible causes:
> Battery voltage removed from PCM
> PCM disconnected
> Dead Battery
> Low battery voltage during cranking
> Battery Disconnected by DRBIII or MDS2
> PCM ground circuit missing.
Name of code: P0891(14) - Transmission Relay
Always On
When monitored: Ignition key is turned from off
position to run position and/or ignition key is
turned from crank position to run position.
Set condition: This code is set if the PCM senses
greater than 3 volts at the Trans Relay Output
(switched battery) terminal of the PCM prior to the
PCM energizing the relay.
Theory of operation: The transmission control
relay is used to supply power to the solenoid pack
when the transmission is in normal operating
mode. When the relay is off, no power is supplied to
the solenoid pack and the transmission is in
Limp-in mode. The relay output is fed back to the
PCM. It is referred to as the Transmission Control
Relay Output circuit or switched battery.
Transmission Effects: The MIL will illuminate
and the transmission system defaults to Logical
Limp-in mode. Logical Limp-in mode results in the
same modes of operation as Limp-in. Since the
relay is stuck "on", the PCM can not open the relay,
and the PCM shifts to 2nd gear.
Possible causes:
> Relay failure (welded contacts)
> Short to battery in 12-volt supply and/or
Transmission Control Relay Output circuit(s)
> Short to voltage
> PCM connector problems
> PCM
Name of code: P0888(15) - Relay Output Always
Off
When monitored: Continuously
Set condition: This code is set when less than 3
volts are present at the Transmission Relay Output
(switched battery) terminals at the PCM when the
PCM is energizing the relay.
Theory of operation: The transmission control
relay is used to supply power to the solenoid pack
when the transmission is in normal operating
mode. When the relay is off, no power is supplied to
the solenoid pack and the transmission is in
Limp-in mode. The relay output is fed back to the
PCM. It is referred to as the Trans Relay Output
circuit or switched battery.
After a controller reset (ignition key turned to
the run position or after cranking engine), the
controller energizes the relay. Prior to this, the
PCM verifies that the contacts are open by check-
ing for no voltage at the switched battery termi-
nals. After the relay is energized, the PCM moni-
tors the terminals to verify that the voltage is
greater than 3 volts.
Transmission Effects: The MIL will illuminates
and the transmission system defaults to Limp-in
mode.
Possible causes:
> Relay failure (intermittent relay function
caused by oxidized or contaminated relay
contacts)
> Short to ground or open circuit in the Trans-
mission Control Relay circuit(s)
> PCM connector problem
> PCM
Name of code: P0725(18) - Engine Speed Sensor
Circuit
NOTE: This code is not a Transmission Input
Speed Sensor DTC
When monitored: Whenever the engine is run-
ning.
Set condition: This code is set when the engine
speed sensed by the PCM is less than 390 RPM or
greater than 8000 RPM for more than 2.0 seconds.
Theory of operation: The PCM uses a new dual
port RAM internal to the controller to send the
Crank Sensor signal to the Transmission Control
System. If the PCM interprets the signal to be out
of range when the engine is running the code is set.
Transmission Effects: The MIL illuminates and
the transmission system defaults to Limp-in mode.
Possible causes:
> Engine DTC (engine rpm related) present.
> PCM
Name of code: P1694(19) - Bus Communication
with Engine Module
When monitored: Continuously with key on.
Set condition: If no PCI bus messages are re-
ceived from the Powertrain Control Module (PCM)
for 10 seconds.
Theory of operation: The PCM uses a new dual
port RAM internal to the controller to communi-
cate with the Transmission Control System. The
Transmission Control System relies on certain en-
gine information to function properly. The Trans-
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