Trans codes 0741 and 1728

[bt96824]

I have a 99 F150 XCAB 4.6 w/ auto trans and recently (2 weeks ago) started getting the blinking OD light. Checked the codes and read P0741 and P1728. After first seeing the OD light blink had the fluid immediately changed and B&M trans cooler installed. OD still comes on after approx 20 mins of freeway driving. When I press the OD button on the freeway I can feel the trans downshift and the RPM's rise about 500. City driving no problem. Is this condition related to the 3000 stall TC thats installed in this trans? It has been in for approx 6 mos without any problems. Thanks for any info you can provide. BTW...I have the SCT Pro Racers tuning package and can make changes to the trans program if necessary.

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[whotnow]

P0741 - Torque Converter Clutch Circ Perf/Stuck off

P1728 - Trans Slip Error

What this means is The T/Q is not locking up fully when it is commanded to. You could have a bad T/Q lock up solinoid on the valve body. Or The T/Q is on its way south. If it goes south it could possibly take the trans with it.

[whotnow]

Depending on your trans setup you should be seeing around 2000 RPM in OD crusing down the highway at 70MPH. When OD/off is pressed at that speed The RPMS should jump to 3500 or so.... Only 500 RPM change = Somethings wrong

[bt96824]

Thanks for the help....I have noticed that the trans shifts and operates normal at low speeds (non-highway). Only after driving on the freeway (approx 2000 rpm@60mph) for a while I notice a change in the feel of the trans (slight vibration) and then the OD light will blink. After that, the shift pressure seems to increase when the trans upshifts through the gears. Turn off the car, start it up again and the OD light is off and the shifting is back to normal until I operate at freeway speeds again.

I received some info (written by Jerry) from the guys at SCT regarding suggested changes to the trans section of the PCM when using a higher stall converter. One function is the "RPM FOR FAILED SPEED SENSOR". Raising the RPM (approx 30 pct) is recommended. Also, adjusting the "LOCKUP SCHEDULE" for the torque converter so it locks earlier (at the 1-2 shift) and dont let it unlock when accelerating.

Any thoughts???

[bt96824]

Could this condition be linked to the PCM not going into "closed loop" mode and preventing the trans from reaching OD during freeway driving?

Will check the O2 sensors and open/closed loop conditions with my datalogger and post results.

[DDan1967]

I seem to be having the same problem as you are. Though It just started and I don't know the codes yet.

I've seen in several threads relating to transmission problems, that they have mentioned the O2 sensor.

Are you and they refering to the Oxygen Sensor mounted in the Exhaust Manifold? Of something totaly different?

Doug

[bt96824]

Yes, they are referring to the O2 sensors located on the the exhaust system.

I just checked the operation of mine this a.m. (using the SCT raptor datalogger) and found they are working o.k. and the PCM is going into closed loop mode.

Ill keep looking for a solution....

[DDan1967]

I know it's been a while but I was wondering if you'd found anything out.

I can't get any codes out of mine. Though I can turn off the flashing light by "clearing" the codes.

I've noticed no driveability problems and it the light only starts flashing when operating at highway speeds for approximatly 30 miles.

I can say that may scanner did tell me that it's working in Closed Loop.

Doug

[01screw]

Doug,
Make sure your scanner is capable of reading Trans. codes. Some only read engine codes and may require the purchase of an "enchanced mode" upgrade package.

[bt96824]

Doug,

Yes I did resolve the problem. Using SCT Advantage software I reset the Torque Converter "Duty Cycle To Lck In" to 1.

No issues after making this change.

Hope this helps.....