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The ECU provides 12 V on pin 53 solenoid valves, and it grounds each individually on pins 5, 30, 32 and 33. Pin 5 is the pressure control valve. Test the resistance across 53 to 5 should be 4.5 to 6.5 ohms 53 to 30 (or 32 or 33) should be 30 to 34 ohms.
Manually actuating this solenoid valve may not always be able to clear anything that is making it stick, but it will be cheaper than having the box out to have it rebuilt if it works for you.
Thanks so much for this post. I was getting severe clunking on the downshift for a few months, that was getting worse and sounding very mechanical. The flex plate and the donut were both good.
I had the oil & filter changed, and the auto guy thought it was just electronic, and said it's too hard to chase electrical gremlins in these boxes.
Last week it started on the upshift as well. After reading this post, I decided to actuate the valves by driving manually. So I'd drive so as to force an upshift or downshift through the gears. After a couple of days of this manual manipulation, the gearbox now shifts smoothly in Drive.
I didn't even get to the point of unplugging the loom in search of oil contamination.
Michael,
Can you please elaborate on how you drove the auto manipulating it as if it were a manual? I'm chasing a similar behaviour in mine. Had the box rebuilt, transfer case rebuilt and still no obvious problem.
Simon
I'm keen to hear how Michael did it too, but I do know you can use a Nanocom to set the gearbox to drive as a manual shift.
I've even had advice from an auto rebuilder to drive it this way when towing heavy loads. Any one else had heard this?
I would imagine all it does is go straight to lock-up.
I keep think the unlocked time is just a LR take on a CVT -- :p:D
To drive it manually just use it as a manual, Instead of putting it in D to take off, use 1 2500rpm, shift to 2 , 2500rpm, shift to 3, 2600rpm, into D, Simple! :) As soon as the revs drop to 2000rpm shift down to 3 again. I drive like that a lot of the time in hills and around town and if I tow anything bigger than a 7x4. I shift it like you use the old 2speed eaton diff splitter, just hold the revs as you change, dont ease off , after a while you get real smooth at it :) And it gives you something to think about, not just sitting there with the slush box doing the work.
Cheers Scott
Thanks for the explanation. Will see how it drives when I get it back and exercise the gears more.
Seems to have made a difference to my auto box after just a couple of days of driving it like a manual.
But the clunk came back :(
But, I've found that if I drive around in 3 (auto) while in the burbs, I don't get the clunking, and only put it into D when I'm cruising at above 60 for some period of time. I'm doing it quite naturally now. So I'm guessing something to do with the gearbox changing from 4th to neutral?