P0740

P0740-TCC OUT OF RANGE

For a complete wiring diagram refer to Diagrams/Electrical. Electrical Diagrams


- When Monitored:

During Electronically Modulated Converter Clutch (EMCC) Operation.

- Set Condition:

Transmission must be in EMCC, with input speed greater than 1750 RPM. TCC/LR Solenoid achieves the maximum duty cycle and can not pull engine speed within 60 RPM of input speed. Also when the transmission is in FEMCC and the engine slips TCC less than 100 RPM for 10 seconds. This DTC can take up to five minutes of problem identification before illuminating the MIL.







Always perform the 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure before proceeding. 45RFE/545RFE Pre-Diagnostic Troubleshooting Procedure


Theory of Operation


When in 2nd, 2nd Prime, 3rd, 4th, or 5th gear, the torque converter clutch (TCC) can be engaged when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the LR Solenoid until the torque converter slip difference (difference between engine and transmission input speed) is within 60 RPM. Then the LR solenoid is fully energized (FEMCC - 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity.


Diagnostic Test


1. DETERMINING IF RELATED DTC P0750 IS PRESENT

With the scan tool, read transmission DTCs.

Is the DTC P0750 present also?

Yes

- Refer to the Transmission category and perform the appropriate symptom.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. 45RFE/545RFE Transmission Verification Test

No

- Go To 2


2. CHECK TO SEE IF DTC P0740 IS CURRENT

With the scan tool, Read and RECORD ALL Transmission DTCs. After recording DTCs, erase DTCs.

Drive the vehicle until the transmission temperature is at least 43� C or 110� F and the engine temperature at least 49� C or 120� F.

Perform the following steps 3 times.

Drive the vehicle to the speed of at least 88 Kmh or 55 mph.

Allow 4th or 5th gear to engage for at least 10 seconds.

Close the throttle.

Tip back into the throttle until the TPS angle is between 25 and 29 degrees.


NOTE: If the throttle angle goes over 30 degrees, you must close the throttle and try again.

Did the TCC engage during any of the attempts, Engine speed approximately equal to input speed?

Yes

- Go To 3

No

- Go To 4


3. INTERMITTENT WIRING AND CONNECTORS

The conditions necessary to set this DTC are not present at this time. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit. Wiggle the wires while checking for shorts and open circuits.

Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.

Wiggle the wires while checking for shorts and open circuits.

With the scan tool, check the DTC EVENT DATA to help identify the conditions in which the DTC was set.

Were there any problems found?

Yes

- Repair as necessary.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. 45RFE/545RFE Transmission Verification Test

No

- Test Complete.


4. LR SOLENOID

With the scan tool, check for other transmission DTC's.

Are the DTCs P1775 and P0841 present also?

Yes

- Replace the Transmission Solenoid/TRS Assembly.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. 45RFE/545RFE Transmission Verification Test

No

- Go To 5


5. TORQUE CONVERTER AND/OR INTERNAL TRANSMISSION

Repair internal transmission as necessary.

Check for the following possible causes.

Inspect the Transmission Oil Pump and Valve Body.

If no problems are found, replace the Transmission Solenoid/TRS Assembly.

Check the Torque Converter Switch Valve and the Torque Converter Clutch Control Valve for sticking in the bore.

Check the Teflon seal rings on the input shaft.

Note: If one of the Input Shaft Teflon seal rings are cut, the loose piece will often lodge in the TCC Switch Valve causing it to jam in its bore.

View repair.

Repair

- In all cases, replace the Torque Converter. Make sure to check all other possible causes in addition to the Torque Converter.
- Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1. 45RFE/545RFE Transmission Verification Test