cincydiesel

What is this P-0740?

vzdude

This says for gas engines, but I can't find any other diagnostics for diesel. Should be the same though.



P0740-TORQ CON CLU, NO RPM DROP AT LOCKUP (GAS)




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 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 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)

1. CHECK IF THERE ANY ENGINE DTCS PRESENT

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Ignition on, engine not running.
With the scan tool, read Engine DTCs.

Is the DTC P0743 also present?

Yes
Refer to the Transmission category and perform the appropriate symptom(s). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)

No
Go To 2



2. CHECK TRANSMISSION FLUID LEVEL

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Check the transmission fluid level.

Is the Transmission fluid level low?

Yes
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 PROCEDURE)

No
Go To 3



3. CHECK TRANSMISSION FLUID

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Check the transmission fluid for contamination or a burnt condition.

Is the Transmission fluid contaminated or burnt?

Yes
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 TCC hydraulic 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



4. CHECK IF THE DTC IS CURRENT

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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 original set conditions.


With the scan tool, read Engine DTCs.

Did the DTC reset?

Yes
Go To 5

No
Go To 9



5. PERFORM TCC SYSTEM TEST

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With the scan tool, perform the TCC System Test.
Follow the instructions on the screen.

Did the engine stall?

Yes
Go To 6

No
Go To 7



6. PERFORM GOV AND 3-4 SHIFT VALVE SYSTEM TEST

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With the scan tool, perform the Gov and 3-4 Shift Valve System Test.
Follow the instructions on the screen.

Did the engine stall?

Yes
Go To 8

No
Go To 7



7. CHECK THE COOLER OUT PRESSURE

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Turn the ignition off to the lock position.
Connect a pressure gauge to the transmission cooler out port with a “T” connector. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - DIAGNOSIS AND TESTING)
Start the engine, with the scan tool, perform the TCC System Test.

Did the cooler out pressure on the gauge increase when the TCC was actuated?

Yes
Remove the transmission oil pump and inspect the reaction shaft, input shaft and input shaft seals for damage or wear and repair or replace as necessary. Replace the Torque Convertor.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)

No
Remove the Valve Body and inspect for an internal blockage or an internal leak in the TCC hydraulic circuit. Repair as necessary. (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/VALVE BODY - REMOVAL)
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (GAS). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)



8. TCC SOLENOID

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Turn the ignition off to the lock position.
Replace the TCC Solenoid per the Service Information (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE/GOVERNOR PRESSURE SENSOR - REMOVAL).
With the scan tool, perform the Gov and 3-4 Shift Valve System Test.
Follow the instructions on the screen.

Did the engine stall?

Yes
Repair internal transmission as necessary. Check for blocked or cross linked passages in the Valve Body. (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
Test Complete.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)



9. INTERMITTENT WIRING AND CONNECTORS

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The conditions necessary set this DTC are not present at this time.
Use the Freeze Frame Data to help duplicate the conditions that set the DTC. Pay particular attention to the DTC set conditions, such as, VSS, MAP, ECT, and Load.
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.
Refer to any technical service bulletins that may apply.

Were there any problems found?

Yes
Repair as necessary.
Perform RE TRANSMISSION VERIFICATION TEST VER - 1 (DIESEL). (Refer to 21 - TRANSMISSION/TRANSAXLE/AUTOMATIC - 48RE - STANDARD PROCEDURE)

No
Test Complete.