Page 4217 of 4284

TEST ACTION APPLICABILITY
9 Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay from the IPM.
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the Fused B+ circuit and the Transmission Control
Relay Output circuit in the IPM.
Ignition on, engine not running.
Measure the voltage of the L/R Pressure Switch Sense circuit in the TCM harness
connector.
Is the voltage above 0.5 volt?All
Ye s®Repair the L/R Pressure Switch Sense circuit for a short to
voltage..
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 10
10 If there are no possible causes remaining, view repair All
Repair
Replace the TCM. WITH THE DRBIIItPERFORM QUICK
LEARN AND REPROGRAM PINION FACTOR.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
11 The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this
circuit.
Wiggle the wiring while checking for shorts and open circuits.
Were there any problems found?All
Ye s®Repair as necessary.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Test Complete.
11 3
TRANSMISSION
P1784-LR PRESSURE SWITCH SENSE CIRCUIT ÐContinued
Page 4218 of 4284
Symptom:
P1787-OD HYDRAULIC PRESSURE TEST FAILURE
When Monitored and Set Condition:
P1787-OD HYDRAULIC PRESSURE TEST FAILURE
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 > 1000 RPM, the TCM
momentarily turns on element pressure to the clutch ckts that don't have pressure to
identify the correct pressure sw closes. If the pressure sw does not close 2 times the code
sets
POSSIBLE CAUSES
INCORRECT FLUID LEVEL
LOSS OF PRIME DTC P1791 PRESENT
RELATED DTC'S PRESENT
INTERMITTENT WIRING AND CONNECTORS
TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
OD PRESSURE SWITCH SENSE CIRCUIT OPEN
OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
OD PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
INTERNAL TRANSMISSION
TCM - O/D HYDRAULIC TEST FAILURE
11 4
TRANSMISSION
Page 4219 of 4284

TEST ACTION APPLICABILITY
1NOTE: Low fluid level can be the cause of many Transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the Service Information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIIIt, read the engine DTC's. Check and repair all engine DTC's prior
to performing Transmission Symptom Diagnostics.
With the DRBIIIt, read Transmission DTC's. Record all DTC's and 1 Trip Failures.
NOTE: Diagnose 1 Trip Failures as a fully matured DTC.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test
for P0705 Check Shifter Signal.
For Gear Ratio DTC's, check and record all CVI's.
Most DTC's set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
NOTE: Verify flash level of Transmission Control Module. Some problems
are corrected by software upgrades to the Transmission Control Module.
NOTE: Check for applicable TSB's related to the symptom.
Perform this procedure prior to Symptom diagnosis.All
Continue
Go To 2
2 With the DRBIIIt, check for other Transmission DTCs.
Is the DTC P1791 present also?All
Ye s®Refer to symptom list and perform test for P1791.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 3
3 With the DRBIIIt, read Transmission DTC's.
Is the DTC P0733 and/or P1781 present also?All
Ye s®Replace the Transmission or Solenoid/Pressure Switch Assembly.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 4
4 With the DRBIIIt, Check the STARTS SINCE SET counter.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?All
Ye s®Go To 5
No®Go To 13
11 5
TRANSMISSION
P1787-OD HYDRAULIC PRESSURE TEST FAILURE ÐContinued
Page 4220 of 4284

TEST ACTION APPLICABILITY
5 Turn the ignition off to the lock position.
CAUTION: Remove the Starter Relay from the IPM. This will prevent the
vehicle from being started in gear.
Install Transmission Simulator, Miller tool #8333 and the FWD Adapter Cable kit,
Miller tool #8333-1.
Note: Check connectors - Clean/repair as necessary.
On the Transmission Simulator select OD on the Pressure Switch selector switch.
With the DRBIIIt, monitor the OD Pressure Switch state while pressing the
Pressure Switch Test button on the Transmission Simulator.
Wiggle the wires leading to the TCM while pressing the button.
Did the O/D Pressure Switch state change to closed and remain closed while wiggling
the wires?All
Ye s®Go To 6
No®Go To 8
6 The Transmission must be above 21É C or 70É F prior to checking fluid level.
Adjusting fluid level on a cold transmission will result in an overfilled transmission.
Check the Transmission Fluid Level per the Service Information.
Is the fluid level OK?All
Ye s®Go To 7
No®Adjust fluid level. Repair cause of incorrect fluid level.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
7 If there are no possible causes remaining, view repair. All
Repair
Disassemble and inspect the Valve Body per service instructions
and repair or replace as necessary. If no problems are found in the
valve body, replace the Transmission Solenoid Pressure Switch
Assembly per the Service Information.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
8 Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/Pressure Switch harness connector.
Remove the Transmission Control Relay from the IPM
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the Fused B+ circuit and the Transmission Control
Relay Output circuit in the Transmission Control Relay connector in the IPM.
Using a 12-volt test light connected to ground, check the Transmission Control Relay
Output circuit in the Solenoid/Pressure Switch Assembly harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s®Go To 9
No®Repair the Transmission Control Relay Output circuit for an open
or high resistance. If the fuse is open make sure to check for a
short to ground.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
11 6
TRANSMISSION
P1787-OD HYDRAULIC PRESSURE TEST FAILURE ÐContinued
Page 4221 of 4284

TEST ACTION APPLICABILITY
9 Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the OD Pressure Switch Sense circuit in
the Transmission Solenoid/Pressure Switch Assembly harness connector..
Is the resistance above 5.0 ohms?All
Ye s®Repair the O/D Pressure Switch Sense circuit for an open.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 10
10 Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the OD Pressure Switch Sense circuit.
Is the resistance below 5.0 ohms?All
Ye s®Repair the OD Pressure Switch Sense circuit for a short to
ground.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 11
11 Turn the ignition off to the lock position.
Disconnect the TCM harness connector.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay from the IPM.
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the Fused B+ circuit and the Transmission Control
Relay Output circuit in the Transmission Control Relay connector in the IPM.
Ignition on, engine not running.
Measure the voltage of the OD Pressure Switch Sense circuit in the TCM harness
connector.
Is the voltage above 0.5 volt?All
Ye s®Repair OD Pressure Switch Sense circuit for a short to voltage.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 12
12 If there are no possible causes remaining, view repair. All
Repair
Replace the TCM. WITH THE DRBIIItPERFORM QUICK
LEARN AND REPROGRAM PINION FACTOR.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
13 The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this
circuit.
Wiggle the wiring while checking for shorts and open circuits.
Were there any problems found?All
Ye s®Repair as necessary.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Test Complete.
11 7
TRANSMISSION
P1787-OD HYDRAULIC PRESSURE TEST FAILURE ÐContinued
Page 4222 of 4284
Symptom:
P1788-2/4 HYDRAULIC PRESSURE TEST FAILURE
When Monitored and Set Condition:
P1788-2/4 HYDRAULIC PRESSURE TEST FAILURE
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 > 1000 RPM, the TCM
momentarily turns on element pressure to the clutch ckts that don't have pressure to
identify the correct pressure sw closes. If the pressure sw does not close 2 times the code
sets.
POSSIBLE CAUSES
LOSS OF PRIME P1791 PRESENT
RELATED DTC'S PRESENT
TRANSMISSION FLUID LEVEL
INTERMITTENT WIRING AND CONNECTORS
TRANSMISSION CONTROL RELAY OUTPUT CIRCUIT OPEN
2/4 PRESSURE SWITCH SENSE CIRCUIT OPEN
2/4 PRESSURE SWITCH SENSE CIRCUIT SHORT TO GROUND
2/4 PRESSURE SWITCH SENSE CIRCUIT SHORT TO VOLTAGE
INTERNAL TRANSMISSION
TCM - 2/4 HYDRAULIC PRESSURE
11 8
TRANSMISSION
Page 4223 of 4284

TEST ACTION APPLICABILITY
1NOTE: Low fluid level can be the cause of many Transmission problems. If
the fluid level is low locate and repair the leak then check and adjust the
fluid level per the Service Information.
NOTE: Always perform diagnostics with a fully charged battery to avoid
false symptoms.
With the DRBIIIt, read the engine DTC's. Check and repair all engine DTC's prior
to performing Transmission Symptom Diagnostics.
With the DRBIIIt, read Transmission DTC's. Record all DTC's and 1 Trip Failures.
NOTE: Diagnose 1 Trip Failures as a fully matured DTC.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
Repair as necessary.
Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test
for P0705 Check Shifter Signal.
For Gear Ratio DTC's, check and record all CVI's.
Most DTC's set on start up but some must be set by driving the vehicle such that all
diagnostic monitors have run.
NOTE: Verify flash level of Transmission Control Module. Some problems
are corrected by software upgrades to the Transmission Control Module.
NOTE: Check for applicable TSB's related to the symptom.
Perform this procedure prior to Symptom diagnosis.All
Continue
Go To 2
2 With the DRBIIIt, check for other Transmission DTCs.
Is the DTC P1791 present also?All
Ye s®Refer to symptom list and perform test for P1791.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 3
3 With the DRBIIIt, read Transmission DTC's.
Is the DTC P0732, P0734 and/or P1782 present also?All
Ye s®Replace the Transmission or Solenoid/Pressure switch assembly.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
No®Go To 4
4 With the DRBIIIt, Check the STARTS SINCE SET counter.
NOTE: This counter only applies to the last DTC set.
Is the STARTS SINCE SET counter 2 or less?All
Ye s®Go To 5
No®Go To 13
11 9
TRANSMISSION
P1788-2/4 HYDRAULIC PRESSURE TEST FAILURE ÐContinued
Page 4224 of 4284

TEST ACTION APPLICABILITY
5 Turn the ignition off to the lock position.
CAUTION: Remove the Starter Relay from the IPM. This will prevent the
vehicle from being started in gear.
Install Transmission Simulator, Miller tool #8333 and the FWD Adapter Cable kit,
Miller tool #8333-1.
Note: Check connectors - Clean/repair as necessary.
Ignition on, engine not running.
On the Transmission Simulator select 2/4 on the Pressure Switch selector switch.
With the DRBIIIt, monitor the 2/4 Pressure Switch state while pressing the Pressure
Switch Test button on the Transmission Simulator.
Wiggle the wiring leading to the TCM while pressing the button.
Did the 2-4 Pressure Switch state change to closed and remain closed while wiggling
the wires?All
Ye s®Go To 6
No®Go To 8
6 The Transmission must be above 70 degree F. prior to checking fluid level. Adjusting
fluid level on a cold transmission will result in an overfilled Transmission.
Check the Transmission Fluid Level per the Service Information.
Is the Transmission Fluid Level at the proper level?All
Ye s®Go To 7
No®Adjust fluid level. Repair cause of incorrect fluid level.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
7 If there are no possible causes remaining, view repair. All
Repair
Disassemble and inspect the Valve Body per service information
and repair or replace as necessary. If there are no problems found
in the Valve Body, replace the Transmission Solenoid/Pressure
Switch Assembly per the Service Information,
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
8 Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid/Pressure Switch Assembly harness connector.
Remove the Transmission Control Relay from the IPM.
Note: Check connectors - Clean/repair as necessary.
Connect a jumper wire between the Fused B+ circuit and Transmission Control Relay
Output circuit in the Transmission Control Relay connector in the IPM.
Using a 12-volt test light connected to ground, check the Transmission Control Relay
Output circuit in the Solenoid/Pressure Switch Assembly harness connector.
NOTE: The test light must illuminate brightly. Compare the brightness to
that of a direct connection to the battery.
Does the test light illuminate brightly?All
Ye s®Go To 9
No®Repair the Transmission Control Relay Output circuit for an open
or high resistance. If the fuse is open make sure to check for a
short to ground.
Perform 41TE TRANSMISSION VERIFICATION TEST - VER 1.
120
TRANSMISSION
P1788-2/4 HYDRAULIC PRESSURE TEST FAILURE ÐContinued