93 toyota pickup sr5 4x4, v6, a340h auto tranny, 180k on the clock.

typical no O/D problem, stays in 3rd gear and shifts high between 1/2 only when everything is warmed up.

when engine is cold it works much better so I'm thinking the viscosity of the fluid is seeping through seals…but ill continue.

-replaced the shift solenoids and filter (old filter had about 50 holes punched in it)
-checked or changed the tps, engine coolant temp sensor, trans oil temp sensor, thermostat, ecm.
-adjusted the tps, kick down cable, throttle cable, floor shifter lever.
-opened and cleaned park/neutral safety switch
-manual shift test works (that's how I've been getting around since this all started) so it should be electrical no?
-burped the coolant and fluid level in the tranny is where it should be.
-replaced cruise control "speed control" ecu

edit: the transmission will sometimes switch in-between gears and work for seconds only.

I've searched for a very long time and have taken about two months to do all this. every other thread ends in new transmission, or a 5spd swap…

any help or validation that the warm fluid is slipping past seals would be greatly appreciated.

thank you
ryan

 

sounds pretty similar to my problem. ive had no luck getting mine figures out yet either. I havent dont the manual shift test yet. How do you do this?

 

climb under the passenger side behind the front wheel, move up close to the engine, you will see the park/neutral safety switch on the transmission(connects to the shift lever) above that is the wire harness, i will check outside on my lunch break but i think its a gray plug, 5 or so wires going into it. unplug it. start the truck and let it warm up.

you will now have to manually shift the truck from L to 2 to D. L is first gear, 2 is third and D is O/D. make sure your rpms are up at 3k when you shift from L to 2. if you can see/feel a difference when you shift manually then the problem should be only electrical. 2 to D is not a huge difference so being higher in the 3k rpms will make the difference clearer.

 

ok cool thanks ill go check this out now

 

Did you run the troubleshooting for the electronic control?
http://personal.utulsa.edu/~nathan-b...34electron.pdf

You could have a bad pattern-select switch (that would delay/prevent shifts to overdrive). The A340H is a very "smart" transmission and can do lots to help you find problems. Let us know what you come up with.

 

how do you determine this if your hood is closed and your driving? when it comes to all the electrical testing im lost as it is all foreign to me haha
this is the part that confuses me. probably something simple and ill get once explained to me a little better
Connect solenoid wire connector and road
test. Does data link connector 1 TT terminal
voltage rise from 0 V to 7 V in sequence?

 

long wires through passenger window or tape the volt meter to your windshield wipers while driving. you could just pop the hood and drive slowly down a residential street. test doesn't require high speed

 

ok i unplugged the grey 6 wire connector and did the manual shifting thing and once in D position and doing 50 the rpms are at 5000-5400....so does it mean my tranny is bad? it has been switched out because the previous tranny was doing the same thing

 

thats high for D, i would think then the problem is mechanical

 

did you O/D light start blinking on the dash?

 

yes it did blink, figured it was just because the connector was disconnected?? pulled the codes anyways and it was 62, 63, 64, 65

 

Hate to tell you this... My 94 did that right before it went out completely. 5 speed swap or rebuild. I went with the swap.

 

Yes, those are the codes you should get with the connector disconnected.

But " and once in D position and doing 50 the rpms are at 5000-5400" is way to high for overdrive; it's too high for 3d. Your transmission is not shifting. There is probably something wrong in the valve body, but that is beyond my skill level.

Sorry I can't help.

 

When it's "warmed up", where is the needle on the temp gauge?

 

right below middle, fan kicks on, that's when i know its up to temp.


took apart my neutral safety switch, CLEAN. put it back together and the truck ran as it should for about 4hours. then dropped out of gear and stayed there. stresses me out when i'm driving.

i have the Electronic Control System pages printed out.

regarding the flow charts:

how do you go about testing the voltage at the ECM? can't test the voltage with the ECM plugged in. ECM terminals unplugged with ignition on gives me no readings of any sort anywhere.

 

First, do NOT jam anything into the mating end of electrical terminals other than the male terminal that's supposed to be in there, you can cause more problems. Bending open the contact inside wrecks the terminal. Go in with your voltmeter probe on the wire side, you can test voltage with it plugged in to the ecu.

 

my probes are too big then, no jamming done here!

see if i can find some paper clips and wrap them around...

edit: both the O/D switch and pattern select switch check out.

thank you shady

 

I hate it when that happens.

 

Does the fluid smell like fire or burn't smell? If so its toast. 5500rpm in D, sorry its slipping.

 

his tranny is toast.
mine is still kickin.

skipped a step by accident, need to unplug the cruise control ecu and volt test OD and E on the ECM. having a hard time unplugging this CC ecu!