Page 2825 of 5267

7.CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN
Measure the resistance of the (F856) 5-volt Supply circuit between the
Line Pressure Sensor/Variable Force Solenoid Assembly harness con-
nector and the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Ye s>>
Repair the (F856) 5-volt Supply circuit for an open.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 8
8.CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND
Disconnect the PCM C1 harness connector.
Disconnect the Line Pressure Sensor/Variable Force Solenoid Assembly
harness connector.
CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller tool #8815 to per-
form diagnosis.
Measure the resistance between ground and the (F856) 5-volt Supply
circuit.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the (F856) 5-volt Supply circuit for a short to ground.
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)
Page 2826 of 5267
9.INTERMITTENT 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 .
Page 2827 of 5267
P0870-OD HYDRAULIC PRESSURE TEST
For a complete wiring diagramRefer to Section 8W.
Page 2828 of 5267

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 don’t have pressure to identify the correct pressure switch closes.
If the pressure switch does not close 2 times the DTC sets.
Possible Causes
LOSS OF PRIME P0944 PRESENT
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
(T9) OD PRESSURE SWITCH SENSE CIRCUIT OPEN
(T9) OD PRESSURE SWITCH CIRCUIT SHORT TO GROUND
(T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
TRANSMISSION SOLENOID/PRESSURE SWITCH ASSEMBLY
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
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.
Diagnostic Test
1.CHECKING FOR LOSS OF PRIME DTC
With the scan tool, check for other Transmission DTCs.
Is the DTC P0944 present also?
Ye s>>
Refer to the Transmission category and perform the appropriate diagnostic procedure.
No>>
Go To 2
2.CHECK FOR RELATED TRANSMISSION DTCS
With the scan tool, read Transmission DTCs.
Are any of the DTCs P0732, P0734 and/or P0846 present also?
Ye s>>
Replace the Transmission Solenoid/Pressure Switch Assembly per the Service Information.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 3
Page 2829 of 5267

3.CHECK TO SEE IF DTC P0870 IS CURRENT
With the scan tool, view DTCs.
Is the status Active for this DTC or is the STARTS SINCE SET counter 2 or less?
Ye s>>
Go To 4
No>>
Go To 9
4.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 Transmission Simulator, turn the Pressure Switch selector switchtoOD.
With the scan tool, monitor the UD Pressure Switch state while pressing thePressure Switch Test button on the
Transmission Simulator.
Wiggle the wires leading to the PCM while pressing and holding the PressureSwitch Test button.
Did the OD Pressure Switch state change to closed and remain closed while wiggling the wires?
Ye s>>
Disassemble and inspect the Valve Body per the Service Information and repair or replace as neces-
sary. If no problems are found in the Valve Body, replace the Transmission Solenoid/Pressure Switch
Assembly.
Perform 42RLE TRANSMISSION VERIFICATION TEST - VER 1. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 5
5.(T9) OD PRESSURE SWITCH SENSE CIRCUIT OPEN
Turn the ignition off to the lock position.
Disconnect the PCM C4 harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly har-
ness connector.
NOTE: Check connectors - Clean/repair as necessary.
CAUTION: Do not probe the PCM harness connectors. Probing the
PCM harness connectors will damage the PCM terminals resulting
in poor terminal to pin connection. Install Miller tool #8815 to per-
form diagnosis.
Measure the resistance of the (T9) OD Pressure Switch Sense circuit
between the Transmission Solenoid/Pressure Switch Assembly harness
connector and the appropriate terminal of Miller tool #8815.
Is the resistance above 5.0 ohms?
Ye s>>
Repair the (T9) OD Pressure Switch Sense circuit for an
open.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 6
Page 2830 of 5267
6.(T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
Measure the resistance between ground and the (T9) OD Pressure
Switch Sense circuit.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the (T9) OD Pressure Switch Sense circuit for a
short to ground.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 7
7.(T9) OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
Ignition on, engine not running.
With the scan tool under TIPM, actuate the Transmission.
Measure the voltage of the (T9) OD Pressure Switch Sense circuit.
Is the voltage above 0.5 volts?
Ye s>>
Repair the (T9) OD Pressure Switch Sense circuit for a
short to voltage.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Go To 8
Page 2831 of 5267

8.(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
With the scan tool under TIPM, actuate the Transmission.
Using a 12-volt test light connected to ground, check (T16) Transmis-
sion Control Output circuit in the Transmission Solenoid/Pressure
Switch Assembly harness connector.
NOTE: The test light must illuminate brightly. Compare the bright-
ness to that of a direct connection to the battery.
Does the test light illuminate brightly?
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/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
No>>
Repair the (T16) Transmission Control Relay Output circuit
for an open. If the fuse is open make sure to check for a
short to ground.
Perform 42RLE TRANSMISSION VERIFICATION TEST -
VER 1. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 42RLE - STANDARD PROCEDURE)
9.INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set the 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.
Were 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 .
Page 2832 of 5267
P0871-OD PRESSURE SWITCH RATIONALITY
For a complete wiring diagramRefer to Section 8W.