7.CHECK THE (T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT FOR A SHORT TO
ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Remove the Transmission Control Relay.
Measure the resistance between the (T118) Governor Pressure Sole-
noid Control circuit and all other circuits in the Transmission Solenoid
Assembly harness connector.
Is the resistance below 5.0 ohms between the (T118) Governor
Pressure Solenoid Control circuit and any other circuit in the
Transmission Solenoid Assembly harness connector?
Ye s>>
Repair the (T118) Governor Pressure Solenoid Control cir-
cuit for a short to another circuit(s).
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 8
8.CHECK THE GOVERNOR PRESSURE SOLENOID
Remove the Transmission Oil Pan per the Service Information. (Refer to 21 -TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE/FLUID - STANDARD PROCEDURE)
Check all internal wiring pertaining to the Governor Pressure Solenoid for an open, short, and bent or broken ter-
minals.
If no internal wiring problems are found, replace the Governor Pressure Solenoid per the Service Information. (Refer
to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/GOVERNOR PRESSURE SENSOR - REMOVAL)
Drive the vehicle performing multiple upshifts and downshifts.
With the scan tool, read Transmission DTCs.
Does the DTC reset?
Ye s>>
Using the schematics as a guide, check the Powertrain Control Module (PCM)pins, terminals, and con-
nectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground
circuits. If no problems are found, replace and program the PCM per the Service Information. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/POWERTRAIN CONTROL MODULE -
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)
Theory of Operation
The Torque Converter Clutch (TCC) Solenoid is used to engage the TCC which improves fuel economy. The Over-
drive Solenoid is used to engage the gear change from third to Overdrive.
When Monitored:
Continuously with the ignition on and the engine running.
Set Condition:
This DTC will set if the expected engine RPM drop does not occur within 4 seconds of the gear change being
requested by the PCM three consecutive failed tests.
Possible Causes
FLUID LEVEL AND CONDITION - EXCESSIVE DEBRIS OR BURNT
3-4 SHIFT SOLENOID
INTERNAL TRANSMISSION FAILURE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
Diagnostic Test
1.CHECK IF THERE ANY TRANSMISSION CONTROL DTCS PRESENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Are there any TIPM TCM Power Control Circuit DTCs also present?
Ye s>>
Refer to the Transmission or Engine category and perform the appropriate symptom(s).
No>>
Go To 2
2.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 3
No>>
Go To 6
3.CHECK THE GOVERNOR AND OVERDRIVE PRESSURE
Turn the ignition off to the lock position.
Connect a 0 - 2068 KPa (0 - 300 PSI) pressure gauge to the Overdrive Clutch test port.
Connect another 0 - 2068 KPa (0 - 300 PSI) pressure gauge to the Governor Pressure test port. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
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.
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)
8.CHECK THE 5 VOLT SUPPLY CIRCUIT FOR AN OPEN - INTERNAL
Remove the transmission oil pan. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE/FLUID - STANDARD PROCEDURE)
Reconnect the Transmission Solenoid Assembly harness connector.
Disconnect the Governor Pressure Sensor connector internal to the
transmission.
Measure the resistance of the 5-volt Supply circuit between the PCM
C2 harness connector and the Governor Pressure sensor connector
internal to the transmission.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 9
No>>
Repair or replace the 5-volt Supply circuit for an open inter-
nal to the transmission.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
9.GOVERNOR PRESSURE SENSOR
Reconnect the PCM harness connectors.
NOTE: The PCM harness connectors must not be disconnected
during this test.
Ignition on, engine not running.
Measure the voltage of the 5-volt Supply circuit at the Governor Pres-
sure Sensor connector internal to the transmission.
Is the voltage between 4.5 and 5.5 volts?
Ye s>>
Replace the Governor Pressure/Transmission Temperature
Sensor per the Service Information. (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 48RE/GOVERNOR
PRESSURE SENSOR - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Using the schematics as a guide, check the Powertrain Control Module (PCM)pins, terminals, and con-
nectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground
circuits. If no problems are found, replace and program the PCM per the Service Information. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/POWERTRAIN CONTROL MODULE -
REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
10.TRANSMISSION - INTERNAL DAMAGE
Turn the ignition off to the lock position.
Remove the transmission oil pan per the Service Information. (Refer to 21 -TRANSMISSION/TRANSAXLE/AUTO-
MATIC - 48RE/FLUID - STANDARD PROCEDURE)
Inspect the transmission oil pan for burnt transmission fluid and/or excessive debris.
Is the transmission fluid burnt and/or contain excessive debris?
Ye s>>
Repair the internal transmission per the Service Information. (Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 48RE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 11
11 .CHECK THE VALVE BODY
Replace the Governor Pressure Solenoid per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE/GOVERNOR PRESSURE SENSOR - REMOVAL)
Install a pressure gauge at the governor pressure test port. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTO-
MATIC - 48RE - DIAGNOSIS AND TESTING)
Start the engine.
Warm the transmission to normal operating temperature.
CAUTION: Apply the brakes.
Place the gear selector in Drive and allow the engine to idle.
Read the governor pressure on the pressure gauge in Drive.
Is the governor pressure on the gauge below 21 kPa (3 psi)?
Ye s>>
Go To 12
No>>
Repair or replace the Valve Body per the Service Information. (Refer to 21 -TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 48RE/VALVE BODY - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
12.VERIFY OPERATION - TEST DRIVE
Remove the pressure gauge from the transmission. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC -
48RE - DIAGNOSIS AND TESTING)
Test drive the vehicle.
Be sure to drive the vehicle at a constant speed of 40-48 Kmh or 25-30 MPH during the drive cycle.
With the scan tool, read Engine DTCs.
Did the DTC reset?
Ye s>>
Using the schematics as a guide, check the Powertrain Control Module (PCM)pins, terminals, and con-
nectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground
circuits. If no problems are found, replace and program the PCM per the Service Information. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/POWERTRAIN CONTROL MODULE -
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)
3.CHECKING FOR GOVERNOR PRESSURE ABOVE 6 PSI
Start the engine.
CAUTION: Apply the parking brake.
Warm the transmission to a normal operating temperature above 43° C (110° F).
CAUTION: Firmly apply the brakes.
With the engine RPM at idle, place the gear selector in Drive.
With the scan tool, read the governor pressure.
Is the governor pressure above 41.4 kPa (6 psi)?
Ye s>>
Go To 4
No>>
Go To 11
4.GOVERNOR PRESSURE MATCH GAUGE PRESSURE
Turn the ignition off to the lock position.
Install a 700 kPa (100 psi) pressure gauge to the Governor Pressure Test Port. (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
Start the engine.
Warm the transmission to a normal operating temperature above 43° C (110° F).
CAUTION: Firmly apply the brakes.
With the engine RPM at idle, place the gear selector in Drive.
With the scan tool, read the governor pressure and compare the scan tool reading to the pressure gauge reading.
Does the scan tool Governor Pressure reading match the pressure gauge reading within 6.9 kPa (1
psi)?
Ye s>>
Go To 5
No>>
Go To 8
5.CHECK FOR BURNT TRANSMISSION FLUID AND/OR EXCESSIVE DEBRIS IN THE TRANSMISSION OIL
PA N
Turn the ignition off to the lock position.
Remove the transmission oil pan per the Service Information and inspect for burnt transmission fluid and excessive
debris. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/FLUID - STANDARD PROCEDURE)
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 6
6.REPLACE THE GOVERNOR PRESSURE SOLENOID AND CHECK THE VALVE BODY
Replace the Governor Pressure Solenoid per with the Service Information.(Refer to 21 - TRANSMISSION/TRANS-
AXLE/AUTOMATIC - 48RE/GOVERNOR PRESSURE SENSOR - REMOVAL)
Start the engine.
Warm the transmission to a normal operating temperature above 43° C (110° F).
CAUTION: Firmly apply the brakes.
With the engine RPM at idle, place the gear selector in Drive.
Read the governor pressure on the pressure gauge.
Is the governor pressure on the pressure gauge above 41.4 kPa (6 psi) with the engine RPM at idle and
the gear selector in Drive?
Ye s>>
Replace the Valve Body per the Service Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE/VALVE BODY - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 7
7.POWERTRAIN CONTROL MODULE
Turn the ignition off to the lock position.
Remove pressure gauge from transmission.
Install the Transmission Oil Pan and refill the transmission fluid per theservice information. (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 48RE/FLUID - STANDARD PROCEDURE)
With the scan tool, erase Engine DTCs.
Test drive the vehicle.
Be sure to stop the vehicle, with the vehicle in drive on six separate occurrences for at least 6 seconds each stop.
With the scan tool, read Engine DTCs.
Did the P1757 DTC reset?
Ye s>>
Using the schematics as a guide, check the Powertrain Control Module (PCM)pins, terminals, and con-
nectors for corrosion, damage, or terminal push out. Pay particular attention to all power and ground
circuits. If no problems are found, replace and program the PCM per the Service Information. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MODULES/POWERTRAIN CONTROL MODULE -
REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 11
8.CHECK THE 5 VOLT SUPPLY CIRCUIT FOR AN OPEN
Turn the ignition off to the lock position.
Disconnect the PCM C2 harness connector.
Disconnect the Transmission Solenoid Assembly harness connector.
Measure the resistance of the 5- volt Supply circuit between the Trans-
mission Solenoid Assembly harness connector and the PCM C2 har-
ness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 9
No>>
Repair the (F856) 5-volt Supply circuit for an open.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)