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At my wits end with my tranny (AW4 shift problems)

clunk

NAXJA Forum User
I have been having all sorts of problems with my AW4 lately: shifting at the wrong time unexpectedly, upshifting, downshifting when holding steady speed..you name it, this AW4 is doing it ALL.
The symptoms:
Sometimes while cruising in 3rd and holding the same speed on flat ground it will decide to shift into 2nd for a few seconds--the RPM's will spike up to 3k then it'll shift back into 3rd and be fine for the rest of the drive. Other times it will do the same thing between 2nd&1st..other times between OD and 3rd..sometimes it'll downshift other times it will upshift.

but heres the kicker which is driving me completely crazy:

It only does it sometimes, whenever it wants to. I have been driving the same road, the same speed with the same amount of weight in the back for the last 4 days and sometimes I'll have problems, the next day it will shift fine. It'll always act up on different sections of the drive. eg: one day it'll be fine driving through town, and start acting up at highway speeds, then the next day it will act up all the way through the city driving and cruise flawlessly on the highway. Sometimes I'll drive 50km's without a flaw and I'll think to myself "it's fixed!" then I'll shut the thing off, do a few errands and get back in only to have the thing shit out on me halfway home.

I have done a slew of adjustments and repairs that I thought had "fixed" the problem but without fail it'll always come back after a few hours of driving. I have adjusted the TV cable, cleaned all the electrical contacts on the TPS, IAC etc, tested and adjusted the TPS(it was only out by .02v), cleaned the IAC, checked the tranny fluid, checked the tranny lines for leaks. Pretty much all of these helped shifting and idle, sometimes even for a few hours but it'll always come back.

everything checks out, but my transmission is still acting up!

What else could be causing the problems? I know the tranny is not dead--the AW4 is bulletproof, and the fact that the problem arises spontaniously and in all different situations leads me to believe it's some kind of an electrical fault somewhere.
any help is greatly appreciated!!
 
PM BrettM, he sells controller units for the AW4 that make it possible to manually control the shifts with the touch of a button.

He might also have some insight as to what is going wrong on yours... Sounds like TCU issues.
 
What year? If it's a Renix, you need to check that the output on the square connector doesn't go floogy as you open the throttle. I'm betting your problem is still the TPS sensor. Next step in my opinion is to try a known good sensor.
 
it's a 1990.
I knew that I had read SOMEWHERE about testing the TPS in closed and WOT position but when I did a search to find the procedure, all I got was the standard voltage test. I'll give the test a try tommorow morning. Would I be best to use my analogue multimeter for this, even though it's a pretty cheap unit?

So to recap, I should turn ignition to ON, engine off. Connect positive to terminal A in the square connector, negative to terminal D in the square connector, note the reading in closed position and slowly open the throttle to WOT by hand using the TV cable and watch for any "hiccups"
what should my end voltage be, or does it matter?
thanks
 
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