Powertrain Control Module (PCM) - 66RFE

P0740-TCC OUT OF RANGE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

When the transmission is in 2nd gear through 6th 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 L/R-TCC Solenoid until the torque converter slip difference (difference between engine and transmission input speed) is within 60 rpm. Then the L/R-TCC solenoid is fully energized (FEMCC - 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity.

- When Monitored:
During Electronically Modulated Converter Clutch (EMCC) Operation.

- Set Condition:
Transmission must be in EMCC with input speed greater than 1750 rpm. The L/R-TCC 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 more than 100 rpm for 10 seconds then DTC P0740 will set. This DTC can take up to five minutes of problem identification before illuminating the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. CHECK FOR RELATED DTC P0750
1. With the scan tool, read DTCs.

Is DTC P0750 present?

Yes

- Testing and Inspection Perform the appropriate diagnostic procedure.

No

- Go To 2

2. CHECK IF THE DTC IS CURRENT
1. With the scan tool, read and RECORD ALL Transmission DTCs. After recording DTCs, erase DTCs.
2. 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.
3. Perform the following steps 3 times.
4. Using the AutoStick(R) (ERS) to place the transmission in 3rd gear.
5. While monitoring the Torque converter slip on the scan tool, accelerate smoothly at light to moderate throttle from 1200 to 2500 engine rpm and watch for TCC engagement.

NOTE: Normal torque converter clutch slippage is 0 (± 20 rpm) in full lock-up.

Pick the one that best describes your findings:

TCC State remained at "Unlock" (controller never commanded TCC engagement)

- Go To 3

Torque Converter Slip dropped properly to 0 (± 20 rpm)

- Go To 4

TCC State showed "Transitioning" or "Full EMCC", but there was little or no change in T/C Slip

- Go To 5

TCC tried to engage but had significant positive slip (60-150 rpm)

- Replace the Torque Converter and remove inspect the Transmission Oil Pump Assembly.
NOTE: Check the input shaft end play before removing the pump. HOLD the input shaft during pump removal to prevent thrust bearings in the input clutches from falling out of position. Split the pump assembly and inspect for torque converter debris. Clean as necessary. Verify the Torque Converter Switch Valve and the Torque Converter Clutch Control Valve (located in the Transmission Oil Pump Valve Body) are not sticking in their bores. Reinstall Transmission Oil Pump Assembly and verify proper input shaft end play.

- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test.

3. CHECK FOR TCC ENGAGEMENT COMMANDED
1. Verify the transmission temperature is at least 43° C or 110° F and the engine temperature at least 49° C or 120° F.
2. Using the scan tool, monitor the "Target Gear TCC State" in the following steps.
3. Road test the vehicle. Using the AutoStick(R) (ERS) in ERS "3", ERS "4", ERS "5" and Drive with an engine speed up to 2500 rpm in each position.

Pick the one that best describes your findings:

TCC would engage properly when commanded

- Go To 4

TCC would NOT engage properly when commanded

- Go To 5

Target Gear TCC State remained in the "Unlock" state continuously

- Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals 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. With the scan tool, perform a Quick Learn.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test

4. CHECK WIRING AND CONNECTORS
1. 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.
2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
3. Wiggle the wires while checking for shorts and open circuits.
4. With the scan tool, check the Event Data to help identify the conditions in which the DTC set.

Were any problems found?

Yes

- Repair as necessary.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test.

No

- Test Complete.

5. CHECK THE L/R-TCC SOLENOID
1. With the scan tool, check for other transmission DTCs.

Are DTCs P1775 and P0841 present?

Yes

- Replace Transmission Solenoid/TRS Assembly.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test.

No

- Go To 6

6. CHECK THE TORQUE CONVERTER AND/OR INTERNAL TRANSMISSION
1. Repair internal transmission as necessary.
2. Check for the following possible causes. Refer to the proper repair procedures.
3. Inspect the Transmission Oil Pump Assembly. Note: Check the input shaft end play before removing the pump. HOLD the input shaft during pump removal to prevent thrust bearings in the input clutches from falling out of position. Split the pump assembly and inspect for torque converter debris. Clean as necessary. Verify that the Torque Converter Switch Valve and the Torque Converter Clutch Control Valve (located in the Transmission Oil Pump Valve Body) are not sticking in their bores. Reinstall Transmission Oil Pump Assembly and verify proper input shaft end play.
4. Check the Teflon seal rings on the input shaft. Note: If one of the seal rings is cut the loose piece will often lodge in the TCC switch valve causing it to stick in its bore.
5. If no problems are found, replace the Transmission Solenoid/TRS Assembly.

Repair

- In all cases, replace the Torque Converter.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test