On my 2006 Ford F150 2WD, v6 automatic, the overdrive dash lamp is blinking, I get a engine light and the code I get is a P0743. That indicates the solenoid or wiring is bad, but everything works just fine. The transmission is running fine, clear fluid - no odor. The overdrive works and the truck shifts like new. When I start, the "OD-OFF" light immediately starts blinking and never changes. I can activate the OD normally and it doesn't effect the blinking light.

Ideas? Where to start? I suspect that since all is functioning well, the issue is with the signal to the ecm? By the way, I can clear the code so that the engine light goes off, but the "OD-OFF" light remains blinking.

 

You prob have a poor connection at the TCC solenoid causing the code. That model truck has a molded leadframe type harness for the trans solenoids and they are bad for loosing contact. The TCC engagement is so subtle you prob don't notice that it's missing.

 

Thanks for the reply,

By TCC engagement...do you mean OD disengagement?

On the highway at 50mph or more I can push the OD-OFF button and it clearly upshifts (overdrive is off)...push the button again and it goes back into overdrive....but the blinking light stays blinking regardless.

I am approaching this as follows: The functionality is perfect - its doing what it should when it should....but I still have a dash light blinking at me from the point I start the truck till I shut it down.

 

TCC is the torque converter clutch. It engages after the truck is in OD to eliminate any slipping in the converter to maximize fuel mileage. It prob only drops the engine RPM down 100-150 when it engages at cruising speeds so unless you are paying attention to it it's hard to feel it engage.

 

So the solenoid is not required to switch the OD on or off?

 

More facts:

This code came up when I had my old ecm replaced with a used one. The old unit gave me P0606 codes so I replaced it. The techs who installed and reprogrammed the new one think that the P0743 was there all the time, but wasn't being reported by the first (bad) ecm...now that I have a (supposedly) good ECM, it is reporting the TCC code.

Of course, my fear is that the new (used) ECM is defective and it is reporting a bad code?

 

The TCC has nothing to do with overdrive.

 

Thanks much for the clarity...I'm learning fast.
Transmissions and women...natures mysteries!

 

Ok, I changed the solenoid and internal "harness"...didnt solve the problem so I assume the issue is electrical from the ecm to the tranny someplace?

At least I was able to confirm that the pan was free of debris, the fluid looked good and the little yellow do-dad was not present so this truck has seen at least one service.

 

Very possible. You need to load test the wire from the PCM connector to the trans connector. Ohm checks are useless. Make sure you don't spread the PCM connector pin they are very small. The pin in question is #36 which is on the smallest PCM connector. Pull back the gray locking lever to release the connector. Looking at the pin side with the gray lever at the top, pin 36 is the second pin from the right on the next to bottom row. The trans connector pin is #3 which looking at the pin side with the lock tab at the top is the second pin from the right on the top row. Connect a bulb to one pin and ground the other, apply power to the other side of the bulb and it should light up bright. If it does, the PCM is bad, if it doesn't you have a wire problem.

 

[QUOTE=70f100longbed;Connect a bulb to one pin and ground the other, apply power to the other side of the bulb and it should light up bright. If it does, the PCM is bad, if it doesn't you have a wire problem.[/QUOTE]


Excellent! Here are the pins that I checked across...no light, so I have a wire problem...please confirm I used the correct pins

Thanks for all your help so far

 

After re-reading your post, I may have been using the wrong side of the connector. My female side doesn't seem to match up with your contacts...see pic below.

Which numbers should I be using to check?

 

You need to test from P to the connector at the transmission. It's white and on the right side at the back just in front of the trans mount.

 

It lights up...can a pcm be fixed or modified? I bought it used, payed for shipping and then paid for reprogramming...$200 down the drain.

 

You should be able to get your money back for the used PCM. They can't be fixed by the average joe to the best of my knowledge. It prob takes specialized equipment to repair one.