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Old 02-14-2005, 01:11 PM
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Unhappy Delayed 1-2 Upshift, 95 Explorer 4R55E


This is my first post on this board after searching the board for similiar problems. I did find one post where it was mentioned the Ford 4R70W tranny often has similiar problem involving a sticking 1-2 accumulator.

My 95 Explorer with the 4.0 L V6 and 4R55E electronically controlled tranny has 150,000 miles on it and was running just great until recently.

A week ago I was getting a flashing 3/4 o/d light and error code on the EEC IV module. I went in and read it with a VOM to get error codes. It gave me diagnostic error code 23 (throttle position sensor out of range) and also a code 646 (transmission 2nd gear failure or incorrect gear ratio in 2nd gear) and a code 647 (3rd gear failure or incorrect gear ratio).

I replaced the throttle position sensor and changed the tranny fluid and filter to try and repair. When replacing the fluid, I noted the magnet in the tranny pan had a very thin layer (maybe 1/32 inch thick), of very fine powder metal particles on it, but I read in a Haynes tranny overhaul book some particles on magnet at this point is normal wear.

After making above repairs/changes, and driving another approx. 25 miles, the 646 error code came back on. Basically, I am noting that the vehicle intermittantly does not shift up from first into second at the normal 15 mph and 2500 rpms unless I take my foot off the throttle after it has raced up to 25 mph and 3500 rpms. I also note it shifts a bit more harshly when I need to get the upshift my taking my foot off the throttle, but I suppose thats to be expected since everything is operating then at a higher than normal upshift torque level.

Does this sound like a 1-2 shift accumulator or sticking valve or leaking gasket etc. type problem ? Anyone know what else I should be looking at to fix this ?

I will likely take it to a tranny shop next, but would like some background info thoughts from anyone familiar with similiar problem to ensure I don't end up getting a full tranny overhaul when its just one or two componets or an adjustment thats needed to properly fix it.

thks in advance,


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Old 02-16-2005, 05:14 AM
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Old 02-16-2005, 07:21 AM
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sounds like the tranny is worn out.

A gear ratio error code is set when the computer 'sees' rpm out of parameters in the program for the gear the tranny is in at the time.

this can happen if the incorrect trany was installed with a different set of planetary gears or the clutch pack is sliping.

did you open the filter to inspect it for stuff that would have been sucked up ?
Dont worry how old you are... it is the mileage on your body that adds up.
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Old 02-16-2005, 11:28 AM
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I took it to a local tranny shop, they dropped pan and inspected and are telling me the intermediate band broken. Said this was causing it to shift from 1st to 3rd. They think it needs a complete rebuild.

Can you see the intermediate band with the pan dropped ? I didn't look myself, just got depressed, and asked them to zip it up so I could limp home to review my next step.

I am thinking of ordering a rebuilt from Arizona and having it shipped to me.

Anybody have any good or bad experience with rebuilds and warranties from PhoenixHardParts or Tammy's Trannys (Auto Medics in Mesa, AZ) or Bob Jones, Chicago, IL ?

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Old 02-18-2005, 08:38 AM
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WARRANTY ISSUES!!! This vehicle is EXTREMELY hard to get the trans in and out of. If it needs to be rebuilt you should consider having a local shop do the work. These trans are NOT cheap. Sofisticated, complex valve body and lots of solenoids. Cooler circuit flow characteristics, proper adjustment, lockup control, MPLS, etc WILL cause havoc with this trans. This being said, it is very common to have a 2nd gear issue with these units.
You will need far more diagnostic tools than a VOM to correctly evaluate the performance of this trans when it is installed.
This is not a weekend warrior project. Most newer vehicles, especially those we use for commuting, will require expert diagnosis and competency to correctly repair. Sorry.
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