NOTE: The governor pressure should rise above 138 kPa (20 PSI). Shortly after the O/D pressure should
rise above 276 kPa (40 PSI).
Did the pressures act as previously described?
Ye s>>
Go To 4
No>>
Go To 5
4.CHECK THE TRANSMISSION OIL CONDITION
Turn the ignition off to the lock position.
Remove the transmission oil pan and inspect for excessive debris and burntoil.
Is the oil burnt or does the transmission oil pan contain excessive debris?
Ye s>>
Repair the transmission as necessary. Refer to the Service Informtion forthe proper repair procedures.
(Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
5.CHECK THE GOVERNOR AND OVERDRIVE PRESSURE AFTER REPLACEMENT OF THE 3-4 SHIFT
SOLENOID
Turn the ignition off to the lock position.
Replace the 3-4 Shift Solenoid per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTO-
MATIC - 48RE/VALVE BODY - DISASSEMBLY)
With the pressure gauges still attached, start the engine and allow the transmission temperature to rise to normal
operating temperature.
CAUTION: Apply the parking brake.
Firmly apply the brakesand place the gear selector in Drive.
While observing the pressure gauges, with the scan tool, select 4th gear from the Gov and 3-4 Shift Valve Test.
NOTE: The governor pressure should rise to above 138 kPa (20 PSI). Shortly after the O/D pressure should
rise above 276 kPa (40 PSI).
Did the pressures act as previously described?
Ye s>>
Te s t C o m p l e t e .
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Overhaul the transmission per the Service Information. Pay attention to seals and clutches related to the
OD clutch.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
When Monitored:
Continuously with the ignition on and engine running.
Set Condition:
The Transmission governor pressure set point is above a threshold while inparkortheP/Nswitchisindrive
during an engine start.
Possible Causes
TRS CONNECTOR DAMAGE OR CORROSION
PCM CONNECTOR DAMAGE OR CORROSION
(T41) P/N POSITION SWITCH SENSE CIRCUIT OPEN
(T41) P/N POSITION SWITCH SENSE CIRCUIT SHORT TO GROUND
(T41) P/N POSITION SWITCH SENSE CIRCUIT SHORT TO ANOTHER CIRCUIT
TRANSMISSION RANGE SENSOR
POWERTRAIN CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Diagnostic Test
1.CHECK IF THE SCAN TOOL DISPLAYS P/N AND D/R IN THE CORRECT POSITION
Ignition on, engine not running.
With the scan tool, monitor the PNP switch input state.
Move the gear selector through all gear positions Park to 1st and back to Park..
Did the scan tool display P/N and D/R in the correct gear positions?
Ye s>>
Go To 8
No>>
Go To 2
2.CHECK THE TRS CONNECTOR FOR DAMAGE OR CORROSION
Turn the ignition off to the lock position.
Disconnect the Transmission Range Sensor harness connector.
Inspect the Transmission Range Sensor harness wiring and connector for damage, pushed out pins, or corrosion,
etc.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 3
3.CHECK THE PCM CONNECTOR FOR DAMAGE OR CORROSION
Disconnect the PCM C1 harness connector.
Inspect the PCM wiring and connector for damage, pushed out pins, or corrosion, etc.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 4
3.CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Connect the TIPM C10 harness connector.
Disconnect the Transmission Solenoid harness connector.
Ignition on, engine not running.
Using the scan tool under the TIPM Actuators, actuate the Transmission
control output.
Using a 12-volt test light connected to ground, check the (T16) Trans-
mission Control Output circuit at the Transmission Solenoid 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>>
Go To 4
No>>
Repair the (T16) Transmission Control Output circuit for an
open.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
4.TOTALLY INTEGRATED POWER MODULE
NOTE: Before continuing, check the TIPM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors.
Pay particular attention to allPower and voltage circuits.
Were any problems found?
Ye s>>
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Replace the Totally Integrated Power Module per Service Information.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
5.INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.
While monitoring the scan tool data relative to this circuit, wiggle test the wiring and connectors.
Look for the data to change or for the DTC to reset during the wiggle test.
Were any problems found?
Ye s>>
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Te s t c o m p l e t e .
When Monitored:
With the ignition on. Battery voltage greater than 10 volts.
Set Condition:
An open condition is detected in the TIPM on the Transmission Control Output circuit.
Possible Causes
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
TOTALLY INTEGRATED POWER MODULE (TIPM)
Diagnostic Test
1.CHECK IF THE DTC IS ACTIVE
Ignition on, engine not running.
With the scan tool, select View DTCs.
Is the status Active for this DTC?
Ye s>>
Go to 2
No>>
Go to 4
2.CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid harness connector.
Ignition on, engine not running.
Using the scan tool under the TIPM Actuators, actuate the Transmission
control output.
Using a 12-volt test light connected to ground, check the (T16) Trans-
mission Control Output circuit at the Transmission Solenoid 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>>
Go To 3
No>>
Repair the (T16) Transmission Control Output circuit for an
open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
3.TOTALLY INTEGRATED POWER MODULE
NOTE: Before continuing, check the TIPM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors.
Pay particular attention to allPower and voltage circuits.
Were any problems found?
Ye s>>
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Replace the Totally Integrated Power Module per Service Information.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
3.CHECK IF THE DTC IS CURRENT
With the scan tool, read Engine DTCs.
Record the Freeze Frame data for the reported DTC.
With the scan tool, erase DTCs.
Turn the ignition off to the lock position.
Using the Freeze Frame data recorded earlier, try to duplicate the conditions in which the DTC originally set.
NOTE: It may be necessary to road test the vehicle to duplicate the originalset conditions.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Ye s>>
Go To 4
No>>
Go To 14
4.VERIFY THE TOW/ HAUL OVERDRIVE FEATURE
NOTE: The transmission fluid temperature must be above 0.0° C (32° F) before proceeding.
With the scan tool, build a custom display using: Engine RPM, Output Shaft Speed, TCC Solenoid, O/D Solenoid
and TPS.
NOTE: This display will monitor the operation of the components.
Start the engine, turn off Overdrive or Tow Haul and test drive the vehicle.
Attain a steady speed of 88.5 Km/h or 55 MPH with a minimum of 1.15 volts throttle opening for 20 seconds.
NOTE: Check the Shift pattern as the vehicle upshifts to speeds of 88.5 Km/hor 55 MPH.
Is the Engine RPM within 60 RPM of the Output Shaft Speed RPM?
Ye s>>
Go To 10
No>>
Go To 5
5.CHECK IF THE OUTPUT SPEED IS GREATER THAN ENGINE RPM
In the previous test, is the Output Shaft Speed greater than Engine RPM?
Ye s>>
Go To 6
No>>
Go To 10
6.CALCULATE EXPECTED ENGINE RPM
With the scan tool, build a custom display using: Engine RPM, Output Shaft Speed, TCC Solenoid, O/D Solenoid
and TPS.
NOTE: This display will monitor the operation of the components.
Start the engine, turn off Overdrive or Tow Haul and test drive the vehicle.
Attain a steady speed of 88.5 Km/h or 55 MPH with a minimum of 1.15 volts throttle opening for 20 seconds.
With the scan tool, verify the 3-4 Solenoid (O/D) Solenoid is on and the TCC solenoid is locked
NOTE: Use this formula, Output Shaft Speed x 0.69 = expected Engine RPM.
Did the Engine RPM drop to 0.69 of the Output Shaft Speed RPM?
Ye s>>
Go To 10
No>>
Go To 7
7.GOVERNOR PRESSURE SYSTEM TEST
Turn the ignition off to the lock position.
Connect a 0 to 2068 kPa or 0 to 300 PSI pressure gauge to the Overdrive Clutch Test Port.
Connect a 0 to 2068 kPa or 0 to 300 PSI pressure gauge to the Governor Test Port.
Start the engine.
NOTE: Allow the transmission temperature to rise to normal operating temperature.
While observing both pressure gauges, select 4th Gear from Gov and 3-4 System Test.
NOTE: The Governor pressure should rise to above 137.8 kPa or 20 PSI, shortly after the OD pressure
should rise above 275.7 kPa or 40 PSI.
Did the pressures act as described?
Ye s>>
Go To 8
No>>
Go To 9
8.CHECK IF THE OIL PAN CONTAINS EXCESSIVE DEBRIS
Remove the transmission oil pan per the Service information.
Is the transmission fluid burnt or does the transmission oil pan contain excessive debris?
Ye s>>
Repair internal transmission as necessary. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC -
48RE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 10
9.CHECK THE 3-4 SHIFT SOLENOID
Turn the ignition off to the lock position.
Replace the 3-4 Solenoid per the Service information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC -
4 8 R E / VA LV E B O D Y - R E M O VA L )
Connect a 0 to 2068 kPa or 0 to 300 PSI pressure gauge to the Overdrive Clutch Test Port.
Connect a 0 to 2068 kPa or 0 to 300 PSI pressure gauge to the Governor Test Port.
Start the engine.
NOTE: Allow the transmission temperature to rise to normal operating temperature.
While observing both pressure gauges, select 4th gear from the Governor 3-4 shift valve system test.
NOTE: The Governor pressure should rise above 137.8 kPa or 20 PSI, shortly after the OD pressure should
rise above 275.7 kPa or 40 PSI.
Did the pressures act as described?
Ye s>>
Te s t C o m p l e t e .
No>>
Overhaul the transmission per the Service Information. Carefully inspect the seals and clutches related
to the OD Clutch. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE -REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
10.TORQUE CONVERTER CLUTCH
Turn the ignition on.
With the scan tool, perform the Torque Converter Clutch test.
Did the engine stall?
Ye s>>
Go To 11
No>>
Go To 13
11 .GOVERNOR/3-4 SHIFT VALVE
Start the engine.
Perform the Governor and 3-4 Shift Valve System Test, select 4th gear.
Did the engine stall?
Ye s>>
Go To 12
No>>
Go To 13
12.TCC SOLENOID
Replace the TCC Solenoid. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/VALVE BODY -
REMOVAL)
With the scan tool, perform the Governor and 3-4 Solenoid test, select 4th gear.
Did the engine stall?
Ye s>>
Repair internal transmission as necessary. Check for blocked passages. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Te s t C o m p l e t e .
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
13.SHAFT OR SEAL DAMAGE
Remove the Transmission Oil Pump per the Service information. (Refer to 21- TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE/OIL PUMP - DISASSEMBLY)
Inspect the Reaction shaft, Input Shaft and Input seal.
Are any of the parts damaged or worn?
Ye s>>
Repair as necessary, also replace the Torque Converter.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Replace the Torque Converter. NOTE: Inspect the Reaction Shaft, Input Shaft and Input Seal. Replace
as necessary if any of the parts are damaged or worn.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
3.CHECK IF THE GOVERNOR PRESSURE IS BELOW 3 PSI
Turn the ignition off to the lock position.
Install a pressure gauge at the Governor Pressure test port. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTO-
MATIC - 48RE - DIAGNOSIS AND TESTING)
NOTE: Use the appropriate pressure gauge for the pressure range measured.
CAUTION: Apply the parking brake.
Start the engine and allow the transmission to reach normal operating temperature above 43° C (110° F).
CAUTION: Apply the brakes.
With the engine at idle, place the gear selector in Drive.
Read the governor pressure on the pressure gauge.
Is the governor pressure on the pressure gauge below 21 kPa (3 psi) with the engine at idle and the
gear selector in Drive?
Ye s>>
The Governor Pressure Solenoid is functioning properly. Go To 7
No>>
Go To 10
4.GOVERNOR PRESSURE BETWEEN 40-55 WITH RELAY REMOVED
Place the gear selector in Park.
Turn the ignition off to the lock position.
Disconnect the TIPM C1 connector.
Start the engine and allow the transmission to reach normal operating temperature above 43° C (110° F).
WARNING: Do not wear loose clothing or jewelry when working on or near a running engine. Failure to
follow these instructions can result in personal injury or death.
NOTE: Disconnecting the TIPM connector may set various DTCs. Disregard anyDTCthatmaysetdueto
disconnecting the connector.
CAUTION: Apply the brakes.
Place the gear selector in Drive and allow the engine to idle for 30 seconds.
With the scan tool, read the Actual Governor Pressure at idle.
Is the governor pressure on the scan tool between 276 - 379 kPa (40 - 55 psi)?
Ye s>>
Go To 5
No>>
Go To 6
5.GOVERNOR PRESSURE SOLENOID
Turn the ignition off to the lock position.
Replace the Governor Pressure Solenoid per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE/GOVERNOR PRESSURE SENSOR - REMOVAL)
Start the engine and allow the transmission to reach normal operating temperature above 43° C (110° F).
With the scan tool, monitor the target governor pressure and actual governor pressure.
Drivethevehicleataconstantspeed40-48Kmh(25-30MPH).
NOTE: The Actual Governor Pressure should be within 21 kPa (3 psi) of the Target Governor Pressure
within 3 seconds.
Is the Actual Governor Pressure within 21 kPa (3 psi) of the Target GovernorPressure?
Ye s>>
Go To 13
No>>
Repair internal transmission leak. Inspect all components pertaining tothe Governor Pressure Sensor
and the Governor Pressure Solenoid. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC -
48RE/GOVERNOR PRESSURE SENSOR - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)