littlebigyota

I have an 89 4wd v6 pickup with an a340h trans. The problem I'm having is no forward or reverse unless. If I rev the engine up it will catch and work perfect until I turn the engine off then back to square one. I did change the lockup and 2 shift someone. The only code it's showing is for the vss#1.

littlebigyota

*solenoids*

scope103

http://personal.utulsa.edu/~nathan-b...31diagnosi.pdf

I'm no transmission expert, but a failure of VSS1 shouldn't keep it from going into gear at all. Could be a bad linkage, but sounds a lot like "fried Transmission."

Let us know how it turns out.

littlebigyota

Thanks for the reply. If it is fried or an expensive fix I my opt for a 5 speed manual swap. If i get time tomorrow I'm going to go to the transmission shop and see what he says.

rustypigeon

Was this happening before you changed the lockup and no. 2 shift solenoid? Why did you change those solenoids?

Does it still have the problem if you manually shift to "L" or "2"?

When you rev the engine and it works, does it make a clunk noise and all of a sudden work?

From the information provided, it sounds like a sticking shift valve in the valve body being overcome by increased line pressure when you rev the engine.

littlebigyota

Yes it was doing it before changing the solenoids. I got codes for the lockup, 2 shift sol

enoids, and vss1 I so I changed the lockup and 2 shift solenoids.

Tried to manual shift but still nothing.

Yes it makes a cluck noise and then works perfect.

If it is a shift valve is this something better left to a trans shop?

rustypigeon

If you have never worked on a transmission before, and you don't have a factory overhaul manual, I would recommend leaving to someone else.

Before you condemn a shift valve, it is a good idea to do a manual shift test. Based on the amount of codes you had for the transmission, this is a good idea. Go to this link and it will tell you what to do...

http://personal.utulsa.edu/~nathan-b...33manualsh.pdf

Basically you unplug the electrical connector to the transmission, then shift through the ranges on your shifter. This removes all electronic control of the transmission, thus eliminating it as the problem. If you can get it to shift using the manual shift test, you have an electrical/electronic problem.

bruno4turbo

so i'm currently swapping a "new" rebuilt a340h into my truck, got my old one filled with water.

I'm a mechanic student, and training to be a trans mechanic. but even i didn't wanna mess with the a340h. if its a stuck valve, probably gonna need a new valve body.

also go to a mom n' pop trans place, not AAMCO or a generic shop like that. they're more likely to throw brake lathe shavings in your oil pan and saying you need a full rebuild. (about $4000 of work)

if you have no forward or reverse, its usually a shift valve. or governor/throttle valve. or your one-way clutch is slipping which is a horrible thing to have slipping...

but like rustypigeon said, check if its not an electrical problem first.

also R&R (just take it out and check it out) is about $800+ so try to get as much info as you can about the problem before taking it to a shop.
the a340h is one of the best transmissions built but they are also one of the hardest to work on (my mentor rebuilt a dozen or so in his carrier)

go to a toyota/japanese import shop as well, not a GM/Ford/Chrysler/European transmission shop. i know it sounds obvious but I gotta buddy that went to a german shop for her engine rebuild on her yota because her neighbor with a benz gets all their work done there... "it was so highly recommended, i don't know why theres still so many problems..."

also a transmission shop will cost you more if you try and take it apart then bring it to them, they won't know if you accidently lost a component even if you didn't. especially automatic trans...

end to end every component in a a340h taken out is about 20-30ft long.

littlebigyota

Just did the manual shift test and still the same.

littlebigyota

A friend of the family owns a trans shop. I talked to him. I'm gona pull the valve body and take it to him to look at and possibly fix. Now all I need is the time to pull it. Thanks rustypigeon and bruno4turbo for your help I'll keep you posted.

bruno4turbo

always nice to have a family member in the trans field haha good luck! don't lose the bolts, theres a lot of em

rustypigeon

And 4 of the 16 bolts are smaller than the rest. Make note of which hole they were in.

bruno4turbo

and don't try to take the valve body apart... theres about 5-10 check balls in them (like little door ways for fluid flow) and they're like little bbs that LOVE to roll under stuff never to be seen again... found that out in transmissions class lol.

littlebigyota

Thanks for the advice.