[dougjpr]

Have a 07 F350 PSD with the auto trans. Am having an occasional problem with a rather severe bang at low speeds(under 20 KM/h). Local dealer said there was nothing wrong because the computer had no fault codes. That didn't sit right with me so I called the dealer I buy from which is further away(another story). Took it into them, they looked at computer codes and also found no faults, but they reprogrammed the computer, not sure which program. Went for a drive with the tech, and the strangest thing happened, the truck still had the severe bang and the best part is the tech was driving it, with laptop connected. I asked him if he thought that was proper, and of course he said no. He said he had to contact Ford as he didn't know where to go from here.

What is happeneing is that in tow/haul mode the trans is shifting from 3rd to first at low speeds. My 05 seemed to hold the gears right down to a stop, in succession, the 07 doesn't seem to do this. Anyone had this problem?

Thanks

Doug

 

[GregH]

The tech is right - without codes for a torqueshift, there isn't a whole lot of direction. He's doing the right thing by "seeking help from above."

Now, everyone knows that the 5R110 is actually a 6 speed transmission, right? One gear is locked out at all times, and the gear that is locked out depends on operating conditions like temperature, tow/haul status, etc.

The tech had the IDS connected during the event, right? So he saw the commanded gear PID change from 3 to 1 about the same time the transmission downshifted. So, it is commanded by the computer. The only other thing is to ensure the correct inputs to the TCM. The TCM thinks it's doing the right thing, based on what it is being told. Is it being told the truth? And finally, if the TCM is being fed correct information, and the transmission is responding to commands, then is the TCM itself interpreting information correctly and issuing appropriate commands? Sometimes this is the hardest question to answer.

So, it is either an issue with inputs, or an issue with the TCM itself..

Probably..

Your tech backed himself into a wall when he answered your question "is this proper?" That is one thing I never do - give a straight up "this is not right" response without adequate time to really investigate an issue. That's also why we frequently call these things "issues" and "concerns" instead of problems...

What if your tech gets into another 07 like yours, and finds it behaves the same way - or worse? Then he's got to go back to you and say "gee, umm, it's supposed to work that way." He's automatically lost credibility.

Anyway, this probably doesn't help you with your transmission concern, but maybe gives you a little insight into us...

 

[jimmy]

does this only happen when tow/haul is used when not actually towing? (empty truck?)

 

[dougjpr]

Jimmy,

Haven't had it happen with trailer on. Only happens sometimes at low speed, like when your stuck on the freeway in rush hour traffic. Truck is in tow/haul because we have a slide in unit that we use for work that is much like a camper, it weighs between 3500 and 4000 lbs depending what we have in it. We take the unit off when we tow. Bang can be so severe that the first time it happened I thought someone hit me. I'll give the dealer a couple of days to check on it, and I'll call back to see what they found. This is the 3rd truck we've leased from this dealer, and I have a friend who is the Bus. Mgr. so the squeeky wheel method works very well for us. I'll post what comes out of this but if anyone has any insight it's much appreciated.

Thanks

Doug

 

[sergeantnic]

Mine does the same thing and it's an 06. Only when I'm unloaded and have the tow/haul mode on. DOn't ask me why I had it on just happened to have it on driving through the mountains one day during vacation and this helashish clunk in the rear end felt like somebody tied my back axle to a tree and I just pulled the tree down. Happened while I was going rather slow and downshifting. SOunds exactly like you are describing it. Please post back if you find a fix.

 

[jimmy]

The transmission is adaptive and my speculation is that the TCM has ramped up pressure to get shift transition time to be within specs with load and unloaded it is too high pressure and too harsh of an engagement.

If the load is light the tow/haul is not really needed and there may be no really good way to load adjust the tow haul downshift in the TCM program strategy.
both the 06's in my drive do what you are talking about but not to the same level of harshness but only when empty. Towing they work great when downshifting.

 

[DesertDave]

I have an '07, and once in a while I use the tow haul mode when I'm empty and in traffic, mostly just to break up the monotony of otherwise suicide-painful stop-and-go SF Bay Area traffic.

Sometimes I forget to turn it off when I exit the freeway. I have had the 'wake up' downshift after several lights, in these instances. Not always, just a couple times.

Not sure if it is a 'problem' or an 'issue' or a 'concern', or none of the above, but it's not a totally unique situation.

For me, since I know the circumstances that cause it, I can avoid it, so it doesn't overly concern me. Unless I read of other problems that this is a symptom of, I doubt I'll bother to mention it, if I ever need to go back to the dealer for service.

 

[sootballz]

My brothers 05 was doing the same thing. The ford tech replaced the pump in the tranny and it fixed the "issue".

 

[dougjpr]

I had an 05 with the same engine, trans and diff. Only difference was that the 05 was 2WD, and the 07 is 4x4. We needed extra weight rating on front axle due to slide in unit. The 05 carried the exact same slide in unit. Put 60,000 km (40,000 mi) and never had an "problem", "issue" or whatever you want to call it like what I have wth this one. Drove it in the exact same manner on the same roads in similar conditions. Maybe I could get it programmed with the same program the 05 had??(not likely). Any way it's kind of frustrating because I'm not sure that tow/haul mode is operating properly. Now that I've mentioned that, what are the downshift points? Right now it only downshifts at 80km/h and 50 km/h. If I have time I may go and pick up the trailer and take it for a drive with a little more load. Trailer weighs approx 10,000.lbs without water, and with what we leave in it. I'll definatley post more info when I get it.

Thanks

Doug

 

[thomhack]

My '05 with the fiver in tow will do this as well (in tow/haul mode). I found that by changing my driving habits I can keep it from that hard down shift. /ubbthreads/images/graemlins/shrug.gif

 

[bclf350]

Mine did the same thing when I was in tow/haul mode going down a steep grade pulling a mini-x. I think I was driving a little too fast when it happend. Since then, I have changed my driving habits as well /ubbthreads/images/graemlins/cool.gif.

 

[dekean867]

My 06 did the same thing after putting on 20k miles. Someone on this forum suggested that I disconnect both batteries for fifteen minutes . Seeing you have no codes this shouldn't hurt anything. I think it just starts from square one again. It worked for me. /ubbthreads/images/graemlins/cool.gif