9.CHECK THE 5 VOLT SUPPLY CIRCUIT FOR AN OPEN INSIDE THE TRANSMISSION
Reconnect the Transmission Solenoid Assembly harness connector.
Remove the transmission oil pan per the Service Information. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/FLUID -
STANDARD PROCEDURE)
Disconnect the Governor Pressure Sensor connector internal to the
transmission.
Measure the resistance of the (F856) 5-volt Supply circuit between the
PCM C2 harness connector and the Transmission Solenoid Assembly
connector internal to the transmission.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 10
No>>
Repair or replace the (F856) 5-volt Supply circuit for an
open internal to the transmission.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
10.CHECK THE ENGINE CONTROL MODULE - 5 VOLT SUPPLY
Reconnect the PCM harness connectors.
Ignition on, engine not running.
Measure the voltage of the (F856) 5-volt Supply circuit in the Governor
Pressure Sensor connector internal to the transmission.
Is the voltage between 4.5 and 5.5 volts?
Ye s>>
Replace the Governor Pressure Sensor per the Service
Information. (Refer to 21 - TRANSMISSION/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 connectors 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)
3.COMPARE SCAN TOOL GOVERNOR PRESSURE READING TO PRESSURE GAUGE READING
Turn the ignition off to the lock position.
Connect 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 and allow the engine to idle.
Warm the transmission to a normal operating temperature above 43° C (110° F).
With the scan tool, read the Governor Pressure and compare the scan tool Governor Pressure reading to the Pres-
sure Gauge reading.
Does the scan tool Governor Pressure reading match the Pressure Gauge reading within 6.9 kPa (1
psi)?
Ye s>>
Go To 4
No>>
Go To 7
4.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 oil and/or excessive debris.
Does the transmission contain burnt oil and/or 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 5
5.CHECK INTERNAL TRANSMISSION FOR A FLUID LEAK
Inspect the transmission for internal fluid leakage in the Valve Body or the Governor Pressure Solenoid. (Refer to 21
- TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/VALVE BODY - REMOVAL)
Were there any problems found?
Ye s>>
Repair the internal transmission as necessary per the Service Information. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE/VALVE BODY - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.VERIFY OPERATION - TEST DRIVE
Remove the pressure gauge from the transmission.
Install the transmission oil pan and refill the transmission per the Service Information. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE/FLUID - STANDARD PROCEDURE)
With the scan tool, erase Engine DTCs.
Test drive the vehicle.
Be sure to stop the vehicle and move the gear selector into the park positionfor a minimum of 5 seconds at least
three times 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.CHECK THE 5 VOLT SUPPLY CIRCUIT FOR AN OPEN - INTERNAL
Reconnect the Transmission Solenoid Assembly harness connector.
Remove the Transmission Oil Pan perthe Service Information. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/FLUID -
STANDARD PROCEDURE)
Disconnect the Governor Pressure Sensor harness 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 be connected 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 Sensor per the Service
Information. (Refer to 21 - TRANSMISSION/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)
6.CHECK THE (T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO ANOTHER
CIRCUIT
Turn the ignition off to the lock position.
Measure the resistance between the (T38) Governor Pressure Sensor
Signal circuit and all other circuits in the Transmission Solenoid Assem-
bly harness connector.
Is the resistance below 100k ohms between the (T38) Governor
Pressure Sensor Signal circuit and any other circuit(s) in the
Transmission Solenoid Assembly harness connector?
Ye s>>
Repair the (T38) Governor Pressure Sensor Signal circuit
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 7
7.CHECK THE (T38) GOVERNOR PRESSURE SENSOR SIGNAL CIRCUIT OR 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 harness connector.
Measure the resistance of the (T38) Governor Pressure Sensor Signal
circuit between the PCM C2 harness connector and the Governor Pres-
sure Sensor harness connector internal to the transmission.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 8
No>>
Replace the Transmission Solenoid Assembly per the Ser-
vice 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/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
5.CHECK THE TRANSMISSION SOLENOID ASSEMBLY
Reconnect the Transmission Solenoid Assembly harness connector.
Remove the Transmission Oil Pan perthe Service Information. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/FLUID -
STANDARD PROCEDURE)
Disconnect the Governor Pressure/Transmission Temperature Sensor
connector (inside transmission).
Measure the resistance between the (T38) Governor Pressure Sensor
Signal circuit and all other circuits in the PCM C1 and C2 harness con-
nectors.
Is the resistance below 100k ohms between the (T38) Governor
Pressure Sensor Signal circuit any other circuit(s) in the PCM
C1 or C2 harness connectors?
Ye s>>
Replace the Transmission Solenoid Assembly per the Ser-
vice Information.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AU-
TOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.CHECK THE GOVERNOR PRESSURE SENSOR SENSOR
Turn the ignition on.
With the scan tool, erase DTCs.
Connect a jumper wire between the (T38) Governor Pressure Sensor
Signal circuit and the (F856) 5-volt Supply circuit in the Governor Pres-
sure Sensor connector.
With the scan tool, read DTCs.
Did the DTC P0868 set?
Ye s>>
Inspect the Governor Pressure Sensor wiring for damage. If
no problems are found, replace the Governor Pressure Sen-
sor per the Service Information.
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)
PRE-DIAGNOSTIC TROUBLE SHOOTING PROCEDURE - 48RE GAS
For a complete wiring diagramRefer to Section 8W
1.
NOTE: Always perform diagnostics with a fully charged battery to avoid false symptoms.
NOTE: Low fluid level can be the cause of many transmission problems. If thefluid level is low locate and
repair the leak then check and adjust the fluid level per the Service Information.
With the scan tool, read engine DTC’s. Check and repair all engine DTCs prior to performing transmission symptom
diagnostics.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary.
Verify the flash level of the Powertrain Control Module. Some problems arecorrected by software upgrades.
Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
Did any of the above checks or procedures correct the symptom?
Ye s>>
Repair is complete.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Refer to the Transmission category and perform the appropriate symptom(s). (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
TRANSMISSION VERIFICATION TEST VER - 1 (GAS)
1.
1. Inspect the vehicle to ensure that all engine and transmission components are properly installed and connected.
Reassemble and reconnect components as necessary.
2. If any existing diagnostic trouble codes have not been repaired, go to Symptom List and follow path specified.
3. Connect a scan tool to the data link connector.
4. Ensure the fuel tank has at least a quarter tank of fuel. Turn off all accessories.
5. Start and run the engine until the transmission temperature is above 43°C(110°F).
6. Check the transmission fluid level per the Service Information. Adjustif necessary.
7. Road test the vehicle. Make 15 to 20 1-2, 2-3 and 3-4 up shifts. Perform these shifts from a standing start to 72
km/h (45 MPH) with a constant throttle opening of 20-25%.
8. Below 40 km/h (25 MPH), make 5 to 8 wide open throttle kick downs to 1st gear. Allow at least 5 seconds each
in 2nd and 3rd between each kick down.
9. For a specific DTC, drive the vehicle in accordance with the Symptom’s When Monitored and Set Conditions to
verify the repair.
10. If a DTC sets during the road test, return to the Symptom List and follow the path. If no DTC sets, the repair is
complete.
Are there any DTCs or symptoms remaining?
Ye s>>
Repair is not complete, refer to appropriate symptom.
No>>
Repair is complete.
Theory of Operation
The Transmission Temperature Sensor is used to sense when the transmissiontemperatureistoohotortoocoldto
operate overdrive and/or the torque convertor clutch. When the transmission sensor detects a temperature below 0°
C (32° F), overdrive and the torque convertor clutch are disabled. When thedetected temperature is above 127° C
(260° F), overdrive is disabled and 3rd gear with TCC is engaged, this strategy is used to increase transmission
fluid flow to help cool the transmission.
When Monitored:
Continuously with the ignition on and the engine running.
Set Condition:
The DTC will set after two consecutive trips in which the transmission oil temperature is greater than 5° C (40°
F) and the transmission oil temperature does not rise more than 8° C (16° F) after 20 minutes of run time with
a vehicle speed greater than 48 Kmh (30 mph). The DTC will also set if the engine temperature is greater than
38° C (100° F) with the transmission oil temperature greater than 127° C (260° F).
Possible Causes
OTHER TRANSMISSION DTC’S SET
INTERMITTENT TRANSMISSION TEMPERATURE SENSOR
TRANSMISSION TEMPERATURE SENSOR
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 DTC IS CURRENT
Ignition on, engine not running.
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 2
No>>
Go To 6
2.CHECK FOR OTHER TRANSMISSION DTCS
Does the scan tool show any Park/Neutral DTCs?
Ye s>>
Refer to the Transmission category and perform the appropriate symptom(s). (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
No>>
Go To 3