wwest Posted January 21, 2010 Report Share Posted January 21, 2010 OK, problem solved. I picked up the car yesterday and tested on some ice last nigh. It appears all is well. What we believe happened is the transfer case control module failed. This caused it to default to FWD, but when the fronts would spin, it would engage harshly, to the point it was a REALLY loud bang. They ended up finding a broken weld on a gear in the PTU. I'm assuming it may have been welded to a shaft? They replaced the PTU and that did it. Let's hope that is it for problems. Ended up in the shop for about 2 weeks out of the initial 4 weeks we owned it. This doesn't make sense. There is NO "transfer" case but let's not be nit-pickly about "labeling". Your equivalent to a transfer case is the rear diff'l case. The torque "transfer" capability, a dual clutch, electromagnetics controlling a mechanical clutch, is housed within the rear diff''l case between the rear end of the drive shaft and the rear diff'l. "...the transfer case control module failed..." Could be, but if so that would be, more likely than otherwise, the end of the story. "... broken weld on a gear in the PTU..." There are NO welds within the PTU but that, again, is sorta picking nits. My guess is that the dealer replaced the control module as first effort, blind trouble-shooting technique, and when that didn't work started looking elsewhere. Ford is footing the bill so why bother to re-install the old control module. On the other hand a faulty control module might very well result in that rear clutch being engaged at times that it should NOT be and I think we already know that the weakest link in the "chain" in that case just happens to be the PTO/PTU. Overstressed, HEAT, the gear teeth begin coming off the ring gear. I would bet that PTO lube smelled HORRID. Quote Link to comment Share on other sites More sharing options...
u0061914 Posted January 21, 2010 Author Report Share Posted January 21, 2010 This doesn't make sense. You could be entirely right. It is also possible that the "service writer" that I was dealing with had no clue as to what he was talking about. I can completely disassemble my vintage broncos and Mustang, but when it comes to the new technology on these cars, I'm still learning. :stats: Quote Link to comment Share on other sites More sharing options...
wwest Posted January 21, 2010 Report Share Posted January 21, 2010 (edited) OK, problem solved. I picked up the car yesterday and tested on some ice last nigh. It appears all is well. What we believe happened is the transfer case control module failed. This caused it to default to FWD, but when the fronts would spin, it would engage harshly, to the point it was a REALLY loud bang. They ended up finding a broken weld on a gear in the PTU. I'm assuming it may have been welded to a shaft? They replaced the PTU and that did it. Let's hope that is it for problems. Ended up in the shop for about 2 weeks out of the initial 4 weeks we owned it. "..This caused it to default to FWD..." Default, no, NOT. Except for two situations it is ALWAYS FWD. Number 1 situation...Acceleration from a stop or from a lower speed, <35MPH, to a higher speed. In this situation, with straight line acceleration, the F/R torque allocation/distribution might be as high as 50/50, tapering off to 100/0 F/R as speed increases, back to FWD mode. Even in a tight acceleration turn the coupling might be as high as 80/20 F/R. Number 2....Simply driving along, cruising along, at a relatively constant speed, ANY speed, and encountering front wheelspin/slip. In this case the rear drive will be instantly engaged, TC will also instantly activate, dethrottling the engine and "hammering" the brakes. Due to a simple matter of physics this latter situation is most likely to happen in lower speed ranges. Probably, maybe, even disabled above ~35MPH. Edited January 21, 2010 by wwest Quote Link to comment Share on other sites More sharing options...
wwest Posted January 21, 2010 Report Share Posted January 21, 2010 (edited) Not the fuse, I check that. If I turn off the traction control and accelerate, the rear wheels will engage, but there will be a very loud "bang" or sometimes the sound of grinding gears, when it tries to engage. I dropped it off this morning at the dealer, so I should know something later this morning. Retrospectively... "...sometimes the sound of grinding gears.." At this point you have now lost some of the PTO ring gear teeth. This has become, is being reported as, a very common failure of this(***) type of F/awd system. Too much use is made of the rear torque coupling, the PTO is overstressed, overheats, blows the seals and/or starts shredding gear teeth. *** Ford, Mazda, and now Venza, RX350, and Sienna. These later three are too new to know what the failure rate might be, become. Mazda, CX-7, seems to have put an end to their PTO failure rate via adding cooling (engine coolant) for the PTO. Edited January 21, 2010 by wwest Quote Link to comment Share on other sites More sharing options...
u0061914 Posted January 21, 2010 Author Report Share Posted January 21, 2010 OK. In situation #2. I had FWD only. No engagement in the rear what so ever. Unless, I accelerated (on ice) excessively, then after a slight lag, the rear would harshly engage, with a loud "bang" Quote Link to comment Share on other sites More sharing options...
bbf2530 Posted January 21, 2010 Report Share Posted January 21, 2010 (edited) EDITED - Reply removed. I replied to an earlier question from page #1 that had already been answered. Edited January 21, 2010 by bbf2530 Quote Link to comment Share on other sites More sharing options...
wwest Posted January 21, 2010 Report Share Posted January 21, 2010 (edited) OK. In situation #2. I had FWD only. No engagement in the rear what so ever. Unless, I accelerated (on ice) excessively, then after a slight lag, the rear would harshly engage, with a loud "bang" MN....Hmmm..... Were it me I think I would seriously consider dumping, QUICKLY, that Edge in favor of something in the Toyota 4runner R/awd class. It appears that the Edge is not only not appropriate for off-road duty, but also not really appropreate for on-road use if driving on that road requires an extraordinary duty-cycle for the F/awd mode, rear drive engaged. One of these days someone will build a R/awd 4runner, or Cayenne, without the extra weight, useless weight 99.9999% of the time, of a "granny-grunt" low range gearbox/transfer case. Edited January 21, 2010 by wwest Quote Link to comment Share on other sites More sharing options...
u0061914 Posted January 21, 2010 Author Report Share Posted January 21, 2010 Nothing extraordinary about the useage. It is strictly a commuter vehicle for my wife. No off road - I have a 71 bronco rock crawler for that. No towing/hauling - I have a 3/4 ton diesel for that. 32 miles a day round trip for her to drive to work each day is about it. Quote Link to comment Share on other sites More sharing options...
wwest Posted January 21, 2010 Report Share Posted January 21, 2010 Nothing extraordinary about the useage. It is strictly a commuter vehicle for my wife. No off road - I have a 71 bronco rock crawler for that. No towing/hauling - I have a 3/4 ton diesel for that. 32 miles a day round trip for her to drive to work each day is about it. It's been quite a few years since I did any computer field service work(***) in MN but back then in the wintertime one of these new F/awd making use of TC would have been quite seriously challenged vs almost any other area of the US, excepting MT and Alaska, of course. For a number of years I had to travel between Seattle and Boston on a fairly regular basis. I quickly learned that if I didn't wish to spent cold winter nights in motels in close proximately to the 3-city airport I had to be sure and route my Northwest flights via Memphis. Thus I have no doubt that your Edge spends about 100X more time in AWD mode than one, say, here in Seattle. *** Weyerhauser box plant in Austin and a semi-conductor fabrication plant right there in Minneapolis. Quote Link to comment Share on other sites More sharing options...
Waldo Posted January 22, 2010 Report Share Posted January 22, 2010 "..This caused it to default to FWD..." Default, no, NOT. Except for two situations it is ALWAYS FWD. This is not true. The Ford AWD system will send a small amount of torque to the rear wheels at ALL times. It is usually as low as about 5% during most highway-type driving, but it's always more than 0. Otherwise the clutches would get cold and when you did want to engage it in your two conditions, it would be abrupt. 2 Quote Link to comment Share on other sites More sharing options...
Waldo Posted January 22, 2010 Report Share Posted January 22, 2010 One of these days someone will build a R/awd 4runner, or Cayenne, without the extra weight, useless weight 99.9999% of the time, of a "granny-grunt" low range gearbox/transfer case. You mean like the Ford Explorer?? Quote Link to comment Share on other sites More sharing options...
wwest Posted January 23, 2010 Report Share Posted January 23, 2010 (edited) You mean like the Ford Explorer?? No. My thinking was more along the lines, "lightweight" lines, of the Toyota Venza or the Mazda CX-7. Edited January 23, 2010 by wwest Quote Link to comment Share on other sites More sharing options...
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