2000 Excursion V10 4R100

I've dug and dug and closest I find is the mechanical diode issue, but this is a v10 and its not all that similar beyond it being a 1-2 shift and RPM thing.

My 1-2 shift seems to be holding on to higher RPM than necessary, 3500 or more, and then shifts hard. But sometimes it shifts gently and at lower RPM. If I let off slightly when its holding on it will shift, I don't have to let off completely.

This happens when trying to bolt out into traffic and getting on it, but it also happens around town and I don't have a lead foot. Its like its in a tow tune and wants to stay in high rpm before shifting, but not always. Like its confused and thinks it under more load than it really is.

Other shifts are fine, but this change in behavior has me wondering. Towed our travel trailer a couple thousand miles recently, no slipping no other problems, no blinking anything, no codes says scangauge (but it may not see trans codes?), temps are good, no leaking.

I haven't serviced the trans and no idea when it was last serviced, but the fluid shows no symptoms of problems on the dipstick. Simply curious if this is a common symptom of something or other before I maybe waste time/money fluid/filter.

Thanks!

 

No 2000 model truck had a mechanical diode. The mechanical diode went into production with the first 2001 truck. So if your's is a 2000 it can't have a mechanical diode. Though your symptoms are those of a failing mechanical diode....what month and year was your truck built? That info will be on the data tag on the B pillar.

 

Thanks Mark,

Yeah the mechanical diode thing just didn't fit as I understood the timeline.

DATE: 02/00

Trans has an orange sticker on it about 4R100 exchange program, see TSB # 99-21 which I'm guessing is a good sign its original.

Its got 192k miles on it btw. And to clarify I towed on it like it is and it hasn't given me any problems other than this annoying shift often.

 

That does clear it from having a mechanical diode. It could be a sticky shift valve in the valve body.

 

That was something I was wondering also, 1-2 shifts are going to be most frequent and things wear out over 16 years... I could fluid/filter and new valve body it. Just didn't want to shotgun parts at it without some other eyes on the symptoms first.

Not sure where better to get eyes on it than here

 

it is common for these transmission to break the accumulator valve springs.

Also common for the accumulator control valves to over stroke and cause the valve to hang in the bore. Sonnax makes a nice replacement valve and reinforces the OEM retainer to prevent the issue from happening again.

1-2 & 2-3 Accumulator Control Valve Kit - 36948-13K - Sonnax