Hello! Long time forum reader, first time poster! I've been reading and using these forms since back in 2013 when I bought my very first Ford and have relied on the wealth of knowledge ever since! Thanks for being a great place with all this priceless information!

Anyways...

Latest Ford unit I have is a 2005 F250 3V V10 4x4 CCSB w/ 135,000 on it. Bought the truck since it was 100% rust free and near mint from across the country (Washington State). Here in Northeast, Ohio - trucks can have noticeable rust just a few years off the lot new! I do not know the history of the truck at all other than it has a 5th wheel hitch in the back so I know it did some sort of heavy towing.

When I received the truck, I went over it: New fluids, new MC plugs/coils (read a lot about these giving folks problems so I just went ahead and replaced them so I'm not worrying about it), new tires, ect. All was good. Slowly but surely, it developed a intermittent torque converter shutter at low RPM when in overdrive. Sometime (not always) the Tow/Haul light would flash and it could at times even kick on the CEL. This is not a problem I wanted to tackle on my own so I opted to take it to the local commercial Ford deal which I know from numerous sources is a highly reputable shop.

Well - going on nearly 2 months later - and 3 "its fixed, come pick it up" events - we're still having the same problem and it's definitely gotten worse.

Error Codes:
P0741
P0660
P1674
P1744
P2105

Here's what they've done (in order):

Replaced TC valve control solenoid - though this would fix problem - did not
Replaced Torque Converter - same - did not fix problem
Replaced internal transmission wiring harness - did not fix problem

Now they are thinking it may be something to do with seals in the valve body.

Although this has been a huge PITA, I honestly can't say anything bad about the shop or the mechanic working on the truck. I paid for the first two repairs but since that did not do the trick - they agreed to troubleshoot and repair until it is fixed - FREE. I am in charge of maintenance activities at work and I know the drill. Sometimes you get a weird one and it takes time and effort to find it - especially intermittent problems.

My thoughts from the beginning is that we are looking at some sort of electrical problem here. We agree that the transmission itself is fine. It shifts beautifully. The issue happens when the trans fluid is hot or cold. The temperature gauge seems to work properly so I don't think it is the trans fluid temp sensor acting up.

Sooner or later they will find the problem and I will most certainly report back but I figured I would reach out for any thoughts?

I suspect that it is either a bad sensor (brake control, TPS, trans temp sensor, ect) or a bad PCM.

Thoughts?

Thanks!

 

I also wonder if its just as simple as a bad ground or the gear shift position sensor.

It's something electrical that is very odd no doubt.

When I'm very very light on the pedal going anywhere from 45-60 in OD you can tell that the Torque Converter doesn't know what to do. It locks and unlocks sporadically. BUT NOT ALWAYS!

If your hard on the gas, it never has the problem.

 

 

As long as they keep focusing on the transmission they will never find the low level misfire in the engine that is causing your problem.

I've very worried that they think it's a seal in the valve body. There are no seals in the valve body.

 

I may have mis-spoken. They believe it could be a seal in the transmission. Not the valve body.

I also was highly suspicious of a misfire but assumed new Motorcraft plugs and coils would prevent that. What else could cause a misfire? Would a misfire trigger the TCC fault each and every time?

Thanks for the reply! I've spent many hours reading your posts and I very much appreciate you spreading your knowledge!

 

No, a misfire should trigger a TCC fault, but I can't say that it is impossible for that to happen.

They can use a scan tool (or Forscan) to watch the misfire monitors to see if they are counting misfires. Either this will demonstrate that it is misfiring, or it will rule it out.

 

The senior service technician working on the truck has been using their Ford scan tool, which I was told shows more than a regular OBD-II unit, to diagnose the problem. He has gone as far as to drive the truck home 30 miles with the computer hooked up and monitoring the condition.

Before he replaced the internal wiring harness, he noted that while he was driving down the freeway, the converter was acting very odd but not shuddering. If I heard him correctly, I believe he said he couldn't get it to lock up (or unlock - I'm not entirely sure).

Either way - they are stumped. Last I heard, they are making calls now to Ford to see where to go next.

Do you still believe there is not a transmission or TC issue?

 

No, with your further explanation I think they are on top of it.

 

Ford engineers are telling the shop to replace the pump now...

The goos news is that the transmissions looks great inside!!

...I'm still thinking we have a bad wire, bad ground, bad sensor, or bad PCM.

 

Update: Problem has been solved! You'll like it!

After approximately 3 months at a commercial Ford truck shop and the following part's:

-2 torque converters (assumed 1st was faulty)
-Trans wiring harness
-TCC shift solenoid
-Complete Trans Valve Body with all new solenoids
-(2) Trans tear downs, yes TWO - (second time was so Fords Engineer could check the mechanics work) - transmission looks excellent inside
-New front pump on transmission
-All new MC plugs and coils

......my problem still persisted. The mechanic was able to "hotwire" the torque converter control circuit to see if it was PCM related. His test "confirmed" that the root cause of the problem was the PCM.

At this point I opted to take the truck home and finish it myself. If the PCM was the actual issue, I could replace that myself. Having done lots of research - I had a hunch....

I removed the alternator (original with 136k on it) and took to an auto parts store for testing. The alternator was charging the battery as it should, but the voltage regulator and diodes failed the test. Replaced alternator.

Problem solved.

 

I had an issue quite similar in that the OEM alternator diodes were not quite to spec, was dealing with what appeared to be a significant parasitic drain. It was also charging the 850 CCA battery, over night it would "leak" down to about 450 CCA. Luckily I know a fantastic alternator/rebuilder who had a replacement on the shelf, needing only to be re-clocked for my application. 2005 E-350 5.4 engine.

Given the increasing complexity and dependence on electronics the alternator and battery become even more important to a good running truck!

Glad you got this sorted--talk about an ordeal.

 

Absolutely! I knew from the beginning that I was probably looking at an electronic related issue given the "intermittent" nature of the shudder. But I let the pros work their magic which obviously didn't turn out well.

Electronics need power, but they also need a clean source of power. As I understand, when the voltage regulator and/or diodes fail, the alternator "works" to charge the battery but supplies the rest of the electronics with a poor energy wave - causing who knows what to occur!

Typically, in my experience, a mechanical problem is repeatable under the same conditions (I.E. operating temp, RPM, ect.) but this one was not. I would see a shudder cold, hot, everyday, then once every 2 weeks, whenever it felt like it basically.

The moral of the story is - if your having a problem that you can't put your finger on, always have the alternator tested (It's Free and Easy to remove/install).

 

Thank you for following up with the fix! I would have not guessed an alternator issue.

Interestingly enough, I was having a very similar issue on a 2004 Lexus LS430. Could not figure it out myself, my mechanic took 2 months to diagnose it. Ended up being the PCM..(I was assuming you were going to follow up saying it was the PCM!)