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P2770-TRANSMISSION TCC CONTROL CIRCUIT HIGH (DIESEL)
For a complete wiring diagramRefer to Section 8W
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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 the Overdrive.
When Monitored:
Continuously with the ignition on.
Set Condition:
This DTC will set if the voltage detected on the Torque Converter Clutch Solenoid Control circuit at the ECM
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 DTC PRESENT
(T75) TCC SOLENOID CONTROL CIRCUIT SHORT TO VOLTAGE
(T75) TCC SOLENOID CONTROL CIRCUIT SHORT TO ANOTHER CIRCUIT
TORQUE CONVERTER CLUTCH SOLENOID
ENGINE 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 FOR ANY TRANSMISSION CONTROL OR TIPM DTCS
Ignition on, engine not running.
With the scan tool, read Engine DTCs.
Are there any Transmission Control or TIPM DTCs present?
Ye s>>
Refer to the Transmission 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 7
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3.CHECK THE (T75) TORQUE CONVERTER CLUTCH SOLENOID CONTROL 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 TCC Solenoid for
an open, short, and bent or broken terminals. If no internal
wiring problems are found, replace the Transmission Sole-
noid Assembly per the Service Information. (Refer to 21 -
TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/VALVE
BODY - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 4
4.CHECK THE (T75) TCC SOLENOID CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
Turn the ignition off to the lock position.
Disconnect the ECM harness connectors.
Ignition on, engine not running.
Measure the voltage of the (T75) TCC Solenoid Control circuit.
Is the voltage above 0.5 volts?
Ye s>>
Repair the (T75) TCC Solenoid Control circuit for a short to
voltage.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 5
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5.CHECK THE (T75) TCC SOLENOID CONTROL CIRCUIT FOR A SHORT TO ANOTHER CIRCUIT
Turn the ignition off to the lock position.
Disconnect the TIPM C10 harness connector.
Measure the resistance between the (T75) TCC Solenoid Control circuit
and all other circuits in the Transmission Solenoid Assembly harness
connector.
Is the resistance below 5.0 ohms between the (T75) TCC Sole-
noid Control circuit and any other circuit(s) in the Transmis-
sion Solenoid Assembly harness connector?
Ye s>>
Repair the (T75) TCC Solenoid Control circuit for a short to
another circuit(s).
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 6
6.ENGINE CONTROL MODULE
Turn the ignition off to the lock position.
Reconnect the ECM harness connectors.
Reconnect the TIPM C10 harness connector.
Turn the ignition on, engine not running.
With the scan tool, actuate the TCC Shift 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.
Does the Test Light cycle on and off and illuminate brightly?
Ye s>>
Go To 7
No>>
Using the schematics as a guide, check the Engine Control
Module (ECM) 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 ECM per the Service Information.
(Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/ENGINE CONTROL MODULE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/
TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)
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7.INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Use the Freeze Frame Data to help duplicate the conditions in which the DTC originally set. Pay particular attention
to the DTC set conditions, such as, VSS, MAP, ECT, and Load
Using the schematics as a guide, visually inspect the related wiring harness. Look for any chafed, pierced, pinched,
or partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken,bent, pushed out, or corroded terminals.
Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
Were there 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>>
Te s t C o m p l e t e .
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*TOW /HAUL OVERDRIVE OFF SWITCH (DIESEL)
For a complete wiring diagramRefer to Section 8W
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Theory of Operation
The tow/haul overdrive OFF (control) switch is located in the shift lever arm. The switch is a momentary contact
device that signals the ECM/PCM to toggle current status of the overdrive function. At ignition on, overdrive oper-
ation is allowed. Pressing the Tow/Haul Overdrive Off switch once causes the Tow/haul Overdrive OFF mode to be
entered and the Tow/Haul lamp to be illuminated. Pressing the switch a second time causes normal overdrive oper-
ationtoberestoredandtheTow/haullamptobeturnedoff.TheTow/haulOverdrive OFF mode defaults to ON after
the ignition switch is cycled OFF and ON. The normal position for the control switch is the ON position. The switch
must be in this position to energize the solenoid and allow a 3-4 upshift. The control switch indicator light illuminates
only when the Tow/haul Overdrive Off switch is turned to the OFF position, or when illuminated by the transmission
control module.
Possible Causes
TOW/HAUL OVERDRIVE OFF SWITCH SENSE CIRCUIT SHORT TO GROUND
TOW/HAUL OVERDRIVE OFF SWITCH
ENGINE CONTROL MODULE
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 8 - ELECTRI-
CAL/ELECTRONIC CONTROL MODULES/TRANSMISSION CONTROL MODULE - DIAGNOSIS AND TESTING)
Diagnostic Test
1.TOW/HAUL OVERDRIVE OFF SWITCH SENSE CIRCUIT SHORT TO GROUND
Turn the ignition off.
Disconnect the ECM C2 harness connector.
Disconnect the Tow/Haul OverdriveOff switch harness connector.
Measure the resistance between ground and the Tow/Haul Overdrive
Off switch sense circuit in the ECM C2 harness connector.
Is the resistance below 5.0 ohms?
Ye s>>
Repair the Tow/Haul Overdrive Off switch sense circuit for a
short to ground.
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Go To 2
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2.CHECK THE TOW/HAUL OVERDRIVE OFF SWITCH
Reconnect the Tow/Haul Overdrive Off switch harness connector.
Measure the resistance between ground and the O/D Tow/Haul Switch
Sense circuit in the ECM C2 harness connector.
Press the Tow/Haul Overdrive Off switch button.
Does the resistance change from above 5.0 ohms to below 5.0
ohms while pressing the Tow/Haul Overdrive Off switch but-
ton?
Ye s>>
Using the schematics as a guide, check the Engine Control
Module (ECM) 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 ECM per the Service Information.
(Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/ENGINE CONTROL MODULE - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER -
1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE - STANDARD PROCEDURE)
No>>
Replace the Tow/Haul Overdrive Off switch per the Service
Information. (Refer to 21 - TRANSMISSION/TRANSAXLE/
AUTOMATIC - 48RE/OVERDRIVE SWITCH - REMOVAL)
STANDARD PROCEDURE