Barry

New to this site, and I have many questions. First off, I have a 1991 Toyota 4WD automatic tranny. I have read many posts pertaining to the problem I have, but have never gotten a straight answer. The tranny shifts into overdrive way too soon sometimes, sometimes it shudders really bad and other times the engines revs up as if it has slipped out of gear, I have tried shifting it manually, and 90 % of the time that helps, but it still does the same thing. I have changed the thermostat, the tranny filter and fluid, adjusted the nuetral safety switch and checked the tps, added Lubeguard to the tranny, nothing has worked. Now the other question I have is that the door jamb states that the truck came out with the A340F tranny, but how do I tell exactly what tranny I have? The shift linkage is on the side of the tranny, I have one fluid pan under the tranny, none under the x-fer case and the x-fer case shifter inside the truck is a stick shift, not the gate type shifter. Part of the wiring harness has been hacked up on the tranny, but I'm not so sure that is the problem because the truck does not act up all the time. Every truck or 4 runner I have looked at has the A340H tranny in it, so I have had no luck finding a wiring harness. I cannot find any Identification numbers on the tranny either. All I see is Aisin Warner, which I know was the manufacturer of this tranny. And if I do have the a340f, I'm not sure if it came out of another truck with a different wiring harness, or if it is the original one and someone just hacked it up changing the motor. My second option is to do a manual swap. My question on that is, can I use all the parts needed off of a 1988 4 runner and bolt up to my 1991 truck? with the exception of maybe having the driveshaft modfied? Will the pedals, tranny&x-fer case, crossmember, etc. all bolt up to my truck? Both the 4 runner and the truck have the 22re in them. Any and all help would be greatly appreciated and I apoligize for the long post, but I cannot seem to get a straight answer from anyone on this, let's just say I have not gotten the same answer twice on anything. Thanks again

toyminator2000

Your truck never came with an A340F from the factory so if it has an A340F then it was swapped in. The biggest difference between the A340F and A340H is that the H model uses a transfer case that shares the trannies ATF for lubrication. The F model has a t-case that uses standard gear lube. If someone swapped in an F model in your truck maybe the electronics from your 91 harness aren't jiving with it. That would also explain the hacked up wiring harness. The only truck that used the F model prior to 1996 was the T100. If you pull a manual tranny from another truck you need to get it from a v6 truck because the bellhousings aren't the same. Its the R150. The pedals, and all the hydraulics are the same on either model. I don't know if you will have any issues with the computer when you put a manual tranny in it.

Also, I think the bolt patterns on the driveshaft flange is different between the manual and auto transmission.

yayfortrees

Automatics aren't exactly my forte, but I would put my money on the wire harness that's hacked up, or a vacuum leak, possibly. Let me guess, somebody cut all the wires on the harness, then spliced them back together using butt connectors and/or electrical tape? All it would take is one loose/dirty/corroded connection to give you an intermittent problem like you're describing.

As far as figuring out exactly what transmission you have, I'm not sure on that. I would keep looking at pictures and/or vehicles to find one with the A340F, and compare.

Good luck, keep us posted!

Barry

Thanks for the replies guys. Toyminator, the vin# on my door jamb and dash match each other, it has never been changed, and the door sticker reads a340f. I had the local toyota dealer run some numbers for me and they also told me that it came out with the f model tranny, so now I am really confused after your reply. I took the shift console out of it yesterday to look at the floorboard, it has never been hacked up or cut in any way to acommodate the 4wd shifter from another transfer case, and the plate that is bolted to the floorboard, the factory paint has never been chipped off of the screws, indicating it was ever removed. I am not questioning your reply, just trying to learn, so please don't take my response the wrong way, I appreaciate your help very much. And on the other questions about the manual swap, why would I have to use one from a v6? The 4 runner I will use has a 22re as well as the truck that I have. The bell housings are the same aren't they? The bell housing that is in the 4 cyl 4 runner will bolt up to my 4 cyl I would think. I don't know about the driveshaft flanges though, never thought about that. Anyway, I welcome more feedback, this is a great site and I appreciate your replies. Thanks again

rustypigeon

^ I agree.

It sounds like your tranny is an a340f. I have an a340f as well. It basically is a manually shifted transfer case, as opposed to the a3340h that uses a solenoid to shift the transfer case.

rustypigeon

He said his door jamb sticker says a340f. So I think an a340f is original equipment for that truck.

angrydogtattoo

I know this is a little old but you have an A340F the difference between the F and the H is that the F is a manual lock out hub and the H is the ADD model, I do believe that the F is ECU controlled for shifting, I think it might be electrical in nature when it shifts premature, or check your linkage, I think it shutters when it shifts too early cause its bogging down the engine.