Theory of Operation
The Torque Converter Clutch (TCC) solenoid is used to engage the TCC which improves fuel economy.
When Monitored:
Continuously with the ignition on.
Set Condition:
This DTC will set if the Torque Convertor Clutch (TCC) can not achieve the desired engine RPM drop when
the TCC Solenoid is near the maximum duty cycle after three consecutive test failures.
Possible Causes
TRANSMISSION FLUID LEVEL LOW OR CONTAMINATED
WORN OR DAMAGED REACTION SHAFT, INPUT SHAFT OR INPUT SHAFT SEALS
BLOCKED OR LEAK IN THE TCC HYDRAULIC CIRCUIT IN THE VALVE BODY
TORQUE CONVERTER CLUTCH SOLENOID
TORQUE CONVERTER
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 21 - TRANSMIS-
SION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
1.CHECK IF THERE ANY ENGINE DTCS PRESENT
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Is the DTC P0743 also present?
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 2
2.CHECK TRANSMISSION FLUID LEVEL
Check the transmission fluid level.
Is the Transmission fluid level low?
Ye s>>
Inspect the transmission, cooler, and lines for leakage and repair as necessary. With the scan tool read
and record the Freeze Frame data for the reported DTC. Erase DTCs and test drive the vehicle to the
conditions in which the DTC originally set. Recheck for DTCs. If the DTC resets, follow the “No” path in
this test procedure and proceed to the next step.
If the DTC does not reset, test is complete, perform RE TRANSMISSION VERIFICATION TEST VER -
1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCE-
DURE)
No>>
Go To 3
3.CHECK TRANSMISSION FLUID
Check the transmission fluid for contamination or a burnt condition.
Is the Transmission fluidcontaminated or burnt?
Ye s>>
Remove the valve body and inspect the components related to the Torque Converter Clutch. (Refer to
21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/VALVE BODY - REMOVAL) Check the valves
for sticking or binding in its bore, internal valve body leakage, or the TCChydraulic circuits plugged with
debris. Repair as necessary. If no problems are found in the Valve Body, replace the Torque Convertor.
(Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/TORQUE CONVERTER-
REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 4
P0743-TORQUE CONVERTER CLUTCH SOLENOID/TRANS RELAY CIRCUITS
For a complete wiring diagramRefer to Section 8W
Theory of Operation
The Torque Converter Clutch (TCC) solenoid is used to engage the TCC which improves fuel economy.
When Monitored:
Continuously with the ignition on.
Set Condition:
This DTC will set if the voltage detected by the PCM for the Torque ConverterClutch SolenoidControl circuit
is different than the expected voltage. Note: To clear this DTC it is necessarytodrivethevehicleatasus-
tained speed which would allow the TCC and/or Overdrive Clutch to operate.
Possible Causes
TRANSMISSION CONTROL OUTPUT DTCS PRESENT
(F941) FUSED IGNITION SWITCH OUTPUT CIRCUIT (RUN-START) OPEN
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT SHORT TO GROUND
(T75) TCC SOLENOID CONTROL CIRCUIT SHORT TO GROUND
(T75) TCC SOLENOID CONTROL CIRCUIT SHORT TO OTHER CIRCUITS
TOTALLY INTEGRATED POWER MODULE (TIPM)
TORQUE CONVERTER CLUTCH SOLENOID
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 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 category and perform the appropriate symptom(s). (Refer to 21 - TRANS-
MISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
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 11
3.CHECK THE (T16) TRANSMISSION CONTROL OUTPUT CIRCUIT
Ignition on, engine not running.
With the scan tool, actuate the Transmission Control Output in the
PCM.
Using a 12-volt test light connected to ground, back probe the (T16)
Transmission Control Output circuit at the TIPM C10 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 cycle on and off and illuminate brightly?
Ye s>>
Go To 4
No>>
Go To 8
4.CHECK THE (T75) TORQUE CONVERTER CLUTCH SOLENOID CIRCUIT
Turn the ignition off to the lock position.
Disconnect the Transmission Solenoid Assembly harness connector.
Ignition on, engine not running.
With the scan tool, actuate the TCC Solenoid.
Using a 12-volt test light connected to 12-volts, check the (T75) TCC
Solenoid Control circuit in the Transmission Solenoid 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 cycle on and off and illuminate brightly?
Ye s>>
Check all internal wiring pertaining to the (T75) TCC Sole-
noid for an open, short, and bent or broken terminals. If no
internal wiring problems are found, replace the Transmis-
sion Solenoid Assembly per the Service Information. (Refer
to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/
VA LV E B O D Y - R E M O VA L )
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 5
Theory of Operation
The Governor Pressure Solenoid is used to control governor pressure. Governor pressure is used to shift between
first, second, and third gear.
When Monitored:
Continuously with the ignition on.
Set Condition:
This DTC will set if the PCM monitored voltage detected on the Governor Pressure Solenoid Control circuit is
different than the expected voltage. Note: To clear this DTC, it is necessary to drive the vehicle at a sustained
speed which would allow the TCC and/or Overdrive Clutch to operate.
Possible Causes
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT SHORT TO GROUND
(T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT OPEN
(T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO GROUND
(T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
(T118) GOVERNOR PRESSURE SOLENOID CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT
GOVERNOR PRESSURE SOLENOID
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 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 category and perform the appropriate symptom.
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 12
Theory of Operation
The 3-4 Solenoid is used the engage the gear change form 3rd gear to 4th gear.
The solenoids used in transmission applications are attached to valves which can be classified as normally open or
normally closed. The normally open solenoid valve is defined as a valve which allows hydraulic flow when no cur-
rent or voltage is applied to the solenoid. The normally closed solenoid valve is defined as a valve which does not
allow hydraulic flow when no current or voltage is applied to the solenoid.These valves perform hydraulic control
functions for the transmission and must therefore be durable and tolerantof dirt particles. For these reasons, the
valves have hardened steel poppets and ball valves. The solenoids operatethe valves directly, which means that
the solenoids must have very high outputs to close the valves against the sizable flow areas and line pressures
found in current transmissions. Fastresponse time is also necessary to ensure accurate control.
When Monitored:
Continuously with ignition on.
Set Condition:
This DTC will set if the voltage detected on the 3-4 Shift Solenoid Control circuit at the PCM is different then
the expected voltage. Note: To clear this DTC it is necessary to drive the vehicle at a sustained speed which
would allow the TCC and/or Overdrive Clutch to operate
Possible Causes
TRANSMISSION CONTROL OUTPUT DTC PRESENT
(T9) 3-4 SOLENOID CONTROL CIRCUIT OPEN
(T16) TRANSMISSION CONTROL OUTPUT CIRCUIT OPEN
(T9) 3-4 SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
(T9) 3-4 SOLENOID CONTROL CIRCUIT SHORT TO GROUND
(T16) TRANSMISSION RELAY OUTPUT CIRCUIT SHORT TO GROUND
(T9) 3-4 SOLENOID CIRCUIT SHORT TO OTHER CIRCUITS
TOTALLY INTEGRATED POWER MODULE
3-4 SHIFT SOLENOID
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 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 category, and perform the appropriate symptom(s).
No>>
Go To 2
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.
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)