P1744 Code in Expedition 4R100 Transmission

[outoforder]

The OD light on my shifter started flashing. I pulled the P1744 code which says the torque converter isn't locking up/excessive slippage. However, the truck still shifts into overdrive. I can push the OD button while it's flashing and the transmission will come out of overdrive. Any thoughts on what exactly is going on inside the transmission?

 

[OVERKILL]

What year, how many miles?

 

[bdcardinal]

Check out the TCC solenoid.

 

[NHGUY]

You can go into OD without TC lockup.That occurs afterwards.Your tc clutch may be shot.

 

[punisher]

Gonna hit you with a couple of different scenarios on this.

One, the TCC (Torque Converter Clutch) is actually slipping, and the code is legit. Could be worn/contaminated clutch, could be a TCC solenoid, off off off chance it could be low line pressure in that circuit. You are likely looking at a hydraulic concern as an electrical problem with the TCC solenoid will set another/additional code.

Two, the PCM just thinks the clutch is slipping. If there is a mismatch between engine RPM and input shaft speed during lockup, you get a MIL light. Years ago TP sensors could cause the code as well because the voltage would jump around and the PCM would look for a locked TCC, at the same time it wasn't commanded on. More common on engines with a separate "closed throttle" switch on the TP sensor.

In a perfect world get a data display, look at Torque converter clutch percentage, TP voltage, RPM, and input shaft RPM, and keep an eye on the MIL lamp. If there is a problem is the RPM of the input shaft higher or lower than the engine RPM? Oh, look up any TSBs or service bulletins regarding this problem. Could be common and there is a known fix. Just a thought.

 

[bdcardinal]

I defer to punisher. This is why you have a tech diag not a parts person.

 

[punisher]

Forgot, trans input shaft RPM is the TSS/Turbine speed Sensor.

 

[Colt45ws]

Yeah, you are going to have to bring it some place and have it daignosed. Or you can throw parts at it, but without looking at why it is throwing that, its just as likely to be a sensor as a cooked converter.