When Monitored:
One time after a reset (ignition key turned to the RUN position or after cranking engine).
Set Condition:
A fault is set if voltage greater than 4.5 volts is detected for 7 msec on any of the pressure switch circuits
before the relay is energized. The transmission is placed in Limp-In. The MIL is on after 10 seconds. of vehicle
operation.
Possible Causes
(T47) 2/4 PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
(T50) L/R PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
(T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
POWERTRAIN CONTROL MODULE
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
The transmission relay is used to supply power to the solenoid pack when in normal operating mode and to turn off
power to produce transmission
limp-inmode. The relay output (which supplies power to the solenoid pack) is fed
back to the controller. It is referred to as SWITCHED BATTERY. After a controller reset (ignition key turned to the
RUN position or after cranking engine), the controller verifies that the relay contacts are open by checking for no
voltage on Switched battery line (transmission control relay output) before the relay is energized. After switched
battery is verified for no voltage, the voltage of each of the solenoid packpressure switches is also checked. Since
the solenoid pack is not powered up, there should be no voltage on any of the pressure switches.
Diagnostic Test
1.CHECK TO SEE IF DTC P0890 IS PRESENT
With the scan tool, view DTCs.
Is the status Active for this DTC or is the STARTS SINCE SET counter set at 0?
Ye s>>
Go To 2
No>>
Go To 5
When Monitored:
Continuously with the ignition on, engine running, with the transmissionin gear.
Set Condition:
The PCM continuously monitors Actual Line Pressure and compares it to DesiredLinePressure.IftheActual
Line Pressure reading is more than 172.4 kPa (25 psi) higher than the Desired Line Pressure, but is less than
the highest Line Pressure ever used in the current gear, the DTC sets.
Possible Causes
RELATED DTC’S PRESENT
LINE PRESSURE CONNECTOR AND WIRING
INTERNAL TRANSMISSION
POWERTRAIN CONTROL MODULE
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure
Sensor (LPS). The desired line pressure is continuously being compared tothe actual line pressure and is regulated
by electronically changing the dutycycle of the Pressure Control Solenoid (PCS). (5% duty cycle = solenoid off =
max line pressure, 62% duty cycle =solenoid on = min line pressure).
The Transmission Control System calculates the desired line pressure based on inputs from the transmission and
engine. A calculated torque input to the transmission is used as the primary input of the desired line pressure cal-
culation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 to 931
kPa (120 to 135 psi) during shifts and in Park and Neutral to ensure consistent shift quality.
Diagnostic Test
1.DETERMINING IF RELATED DTCS ARE PRESENT
With the scan tool, check for other transmission DTCs.
Are there any other line pressure related DTCs present?
Ye s>>
Refer to the Transmission category and perform the appropriate symptom. Perform the test for P0934
and/or P0935 first if present.
No>>
Go To 2
2.COMPARE ACTUAL LINE PRESSURE TO DESIRED LINE PRESSURE
CAUTION: Apply Parking Brake
Start the engine.
CAUTION: Firmly apply the brakes.
With the scan tool, monitor the Line Pressure, Desired Line Pressure and the TPS degrees.
While firmly applying the brakes, place the shifter in reverse, then slowly press the accelerator pedal to a TPS
degree of 15°.
Compare the Line Pressure reading to the Desired Line Pressure reading on the scan tool.
Does the Line Pressure stay within ± 34 kPa or 5 psi of the Desired Line Pressure?
No>>
Go To 3
Ye s>>
Go To 5
3.CHECK LINE PRESSURE CONNECTOR AND WIRING
Ignition on, engine not running.
With the scan tool, monitor the Line Pressure Sensor voltage while wiggling the wiring harness and connectors
pertaining to the Line Pressure Sensor/Variable Force Solenoid Assembly.
Did the voltage remain steady while wiggling the wiring harness and connectors?
Ye s>>
Go To 4
No>>
Disconnect and properly reconnect the Line Pressure Sensor/Variable Force Solenoid Assembly con-
nector. Inspect terminals and repair as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
4.CHECK PCM AND WIRING
Turn the ignition off to the lock position.
Remove the Ignition Switch Feed fuse from the TIPM.
CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being
startedingear.
WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in
personal injury or death.
Install the Transmission Simulator,Miller tool #8333 and the ElectronicTransmission Adapter kit.
With the Transmission Simulator select the
OFFposition on theInput/Output Speedswitch.
Ignition on, engine not running.
With the scan tool, monitor the Line Pressure during the following step.
With the Transmission Simulator, turn the selector switch to each of the 3 Line Pressure positions.
NOTE: All three scan tool Line Pressure readings should be steady and ± 14 kPa or 2.0 psi of the reading
specified on the Transmission Simulator.
Did the Line Pressure read within ± 14 kPa or 2.0 psi in all three positions?
Ye s>>
Using the schematics as a guide, check the Powertrain Control Module (PCM)terminals for corrosion,
damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems
are found, replace the PCM per the Service Information. With the scan tool,perform QUICK LEARN.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Repair internal transmission and inspect the oil pump per the Service information and replace if neces-
sary. If no problems are found, replace the Line Pressure Sensor/VariableForce Solenoid Assembly —
possible cause is the Pressure Control Solenoid is stuck.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
5.CHECK WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specifictothiscircuit.
Wiggle the wires while checking for shorted and open circuits.
With the scan tool, check the DTC EVENT DATA to help identify the conditionsin which the DTC was set.
Where there any problems found?
Ye s>>
Repair as necessary.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Te s t C o m p l e t e .
When Monitored:
Continuously with the ignition on and engine running.
Set Condition:
This DTC will set when the monitored Line Pressure Sensor voltage is less than or equal to 0.35 volts for 0.18
seconds.
Possible Causes
(F856) 5-VOLT SUPPLY CIRCUIT OPEN
(F856) 5-VOLT SUPPLY CIRCUIT SHORT TO GROUND
(T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO GROUND
LINE PRESSURE SENSOR
POWERTRAIN CONTROL MODULE
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure
Sensor (LPS). The desired line pressure is continuously being compared tothe actual line pressure and is regulated
by electronically changing the dutycycle of the Pressure Control Solenoid (PCS). (5% duty cycle = solenoid off =
max line pressure, 62% duty cycle =solenoid on = min line pressure).
The Transmission Control System calculates the desired line pressure based on inputs from the transmission and
engine. A calculated torque input to the transmission is used as the primary input of the desired line pressure cal-
culation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 to 931
kPa (120 to 135 PSI) during shifts and in Park and Neutral to ensure consistent shift quality.
The monitored Line Pressure Sensor voltage should always be between 0.35 and 4.75 volts. Any monitored volt-
ages outside these parameters indicate an Line Pressure Sensor or wiring problem and will cause either DTC
P0934 or P0935 to set.
Diagnostic Test
1.CHECK IF DTC IS CURRENT
With the scan tool, check the STARTS SINCE SET counter for P0934.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?
Ye s>>
Go To 2
No>>
Go To 6
2.CHECK THE PCM AND WIRING
Turn the ignition off to the lock position.
Remove the Ignition Switch Feed fuse from the TIPM.
CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being
startedingear.
WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in
personal injury or death.
Install the Transmission Simulator,Miller tool #8333 and the ElectronicTransmission Adapter kit.
Ignition on, engine not running.
With the scan tool, under Transmission Sensors, monitor the Line Pressure.
Using the Transmission Simulator, set the rotary switch to each of the 3 line pressure positions.
When Monitored:
Continuously with ignition on and engine running.
Set Condition:
This DTC will set if the monitored Line Pressure Sensor voltage is greater than or equal to 4.75 volts for the
period of 0.18 seconds
Possible Causes
(T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT OPEN
(K900) SENSOR GROUND CIRCUIT OPEN
(T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
LINE PRESSURE SENSOR
POWERTRAIN CONTROL MODULE
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
Line pressure is electronically controlled by the Transmission Control System and is measured by the Line Pressure
Sensor (LPS). The desired line pressure is continuously being compared tothe actual line pressure and is regulated
by electronically changing the dutycycle of the Pressure Control Solenoid (PCS). (5% duty cycle = solenoid off =
max line pressure, 62% duty cycle =solenoid on = min line pressure).
The Transmission Control System calculates the desired line pressure based on inputs from the transmission and
engine. A calculated torque input to the transmission is used as the primary input of the desired line pressure cal-
culation and is called Torque Based Line Pressure. In addition, the line pressure is set to a preset level 827 to 931
kPa (120 to 135 PSI) during shifts and in Park and Neutral to ensure consistent shift quality.
The monitored Line Pressure Sensor voltage should always be between 0.35 and 4.75 volts. Any monitored volt-
ages outside these parameters indicate an Line Pressure Sensor or wiring problem and will cause either DTC
P0934 or P0935 to set.
Diagnostic Test
1.CHECK TO SEE IF DTC IS CURRENT
With the scan tool, Check the STARTS SINCE SET counter for P0935.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?
Ye s>>
Go To 2
No>>
Go To 6
2.CHECK THE PCM AND WIRING
Turn the ignition off to the lock position.
Remove the Starter Relay.
Remove the Ignition Switch Feed fuse from the TIPM.
CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being
startedingear.
WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in
personal injury or death.
Install the Transmission Simulator,Miller tool #8333 and the ElectronicTransmission Adapter kit.
Ignition on, engine not running.
With the scan tool, monitor the Line Pressure.
Using the Transmission Simulator, set the rotary switch to each of the 3 line pressure positions.
4.CHECK THE (T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT FOR AN OPEN
Disconnect the PCM C4 harness connector and connect Miller tool
#8815.
Measure the resistance of the (T38) Line Pressure Sensor Signal circuit
from the Line Pressure Sensor/Variable Force Solenoid Assembly har-
ness connector to the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Ye s>>
Repair the (T38) Line Pressure Sensor Signal circuit for an
open.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 5
5.CHECK THE (T38) LINE PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
Ignition on, engine not running.
With the scan tool under TIPM, actuate the Transmission.
Measure the voltage of the (T38) Line Pressure Sensor Signal circuit.
Is the voltage above 5.5 volts?
Ye s>>
Repair the (T38) Line Pressure Sensor Signal circuit for a
short to voltage.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Using the schematics as a guide, check the Powertrain
Control Module (PCM) terminals for corrosion, damage, or
terminal push out. Pay particular attention to all power and
ground circuits. If no problems are found, replace the PCM
per the Service Information.With the scan tool, perform
QUICK LEARN.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
P0944-LOSS OF HYDRAULIC PUMP PRIME
For a complete wiring diagramRefer to Section 8W.
When Monitored:
Every 350 msec
Set Condition:
If the transmission begins to slip in any forward gear, and the pressure switch or switches that should be
closed for a given gear are open, a loss of prime test begins. All available elements (in 1st gear LR, 2/4 and
OD, in 2nd, 3rd, and 4th gear 2/4 and OD) are turned on by the PCM to see if pump prime exists. The code
is set if none of the pressure switches respond. The PCM will continue to runthe loss of prime test until pump
pressure returns. The vehicle will not move or the transmission will slip.Normal operation will continue if pump
prime returns.
Possible Causes
LOW TRANSMISSION FLUID LEVEL
SHIFT LEVER POSITION
PLUGGED TRANSMISSION FILTER
TRANSMISSION OIL PUMP
Always perform the 42RLE Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
Theory of Operation
The Loss of Prime Test is used to prevent transmission defaults and erroneous fault codes during temporary loss of
pump prime that may occur with low transmission fluid under severe brakingconditions, start-up, etc. and to point
towards more subtle problems such as a plugged or ruptured oil filter. The Loss of Prime fault is set by a loss of
hydraulic pressure in the transmission system. This condition, if sustained, will result in the vehicle being unable to
move.
Diagnostic Test
1.CHECK TO SEE IF DTC P0944 IS CURRENT
Place the gear selector in park.
Start the engine.
NOTE: The Transmission Temperature must be at least 43° C (110° F) before performing the following steps.
The Transmission must be at operating temperature prior to checking pressure. Cold transmission fluid will result in
higher pressure readings.
Place the Transmission in Reverse.
With the scan tool, observe the Transmission Pressure Switch states.
Are any of the Pressure Switches closed?
Ye s>>
Go To 2
No>>
Go To 4
P0992-2/4/OD HYDRAULIC PRESSURE TEST
For a complete wiring diagramRefer to Section 8W.
When Monitored:
In any forward gear with engine speed above 1000 RPM, shortly after a shift and every minute thereafter.
Set Condition:
After a shift into a forward gear, with engine speed greater than 1000 RPM, the PCM momentarily turns on
element pressure to the clutch circuits that do not have pressure to identify that the correct pressure switch
closes. If the pressure switch does not close 2 times the DTC sets.
Possible Causes
CONDITION P0992 PRESENT
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 42RLE - DIAGNOSIS AND TESTING).
Theory of Operation
Pressure switches are normally off or open (no pressure applied) and read high (+12 volts). When an element is
applied, the corresponding pressure switch closes to ground (0 volts) or turns on. The controller tests the OD and
2/4 pressure switches when they are off (when the corresponding friction element is not applied) by briefly applying
the OD and 2/4 elements which will cause the corresponding pressure switchto close. The test verifies that the
switches are operational and that the switch will close when the corresponding element is applied. If a switch fails
to respond, it is re-tested. The MIL illuminates and the transmission system defaults to Limp-in mode.
1.CHECK TO SEE IF DTC P0992 IS CURRENT
NOTE: The vehicle must be driven to set this DTC. The transmission must at operating temperature with the
Engine RPM above 1000 RPM.
This DTC is an indication of both the 2/4 and the O/D Hydraulic Pressure Switch DTCs present.
Perform the diagnostic procedures for both P0845 and P0870.
With the scan tool, check the DTC EVENT DATA to help identify the conditionsin which the DTC was set.
If there are no possible causes remaining, view repair.
Repair
Refer to the Transmission category and perform the diagnostic proceduresfor P0845 and P0870.