P0743 Ford F150: Comprehensive Guide to Diagnosis and Solution

Today, we are dealing with a 2014 Ford Triton 5 where the customer has replaced the transmission recently. However, they are now experiencing issues with the overdrive cancel light flashing and the check engine light on. We will scan the vehicle to understand the nature of the problem.

Upon scanning, we found memory codes related to output speed sensors, torque converter flex full TCC system electrical fault, and intake runner control stuck. These codes seemed unrelated to the problem at hand.

During a road test, we monitored the output shaft speed, turbine shaft speed, and vehicle speed signals and found no issues with the signals. However, the transmission remained in a fault mode inhibiting overdrive, likely due to the torque converter circuit.

On further inspection, we checked the resistance of pins 1 and 2 of the TCC solenoid using an ohmmeter and found a realistic reading. We also conducted a running self-test to clear any potential issues caused by the presence of transmission fluid inside the connector.

After the running self-test, we observed that the intake manifold control did not return. We then conducted another road test and observed the transmission fault appearing after a certain distance. We attempted to command the torque converter clutch solenoid on and off but were unable to do so.

Our next step involved identifying the pins in the computer that control the TCC solenoid and testing for resistance while manipulating the wires to spot any intermittent breaks or opens in the circuit. However, no differences were noted despite extensive testing.

After trying various troubleshooting methods, including cleaning the harness and manipulating the connector, we concluded that the issue likely resides within the transmission itself, possibly involving the TCC solenoid connection.

Overall, this scenario serves as a reminder of the complexities involved in diagnosing and resolving transmission issues, and the importance of thorough testing to pinpoint the root cause.

What are the fault codes for the transmission?

Memory codes, output speed sensors no signal, torque converter flex full TCC system electrical fault, and intake runner control stuck.

What was the resistance measured for the TCC solenoid circuit?

The resistance measured for the TCC solenoid circuit was 15 ohms, which was considered a realistic number.

Did the wiggling of wires and harness affect the transmission issue?

No, wiggling the wires and harness did not make a difference, indicating that the problem might be internal.

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