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2JZ S13
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Hey guy's the a340e is not shifting into overdrive.

i thought i might be the transmission so i put a new one in as well as a new differant converter, still has the same exact issue. even put toyota type 4 in it. tried a friends ECU. still act's the same way.

what can i check/do?

TPS set wrong/bad?
Coolant temp sensor? (will be replaced tonight)
Anything else to try? i did the manual test and it say's either a bad ecu (which i tried a new one) or a bad neutral safty switch (the guy i got the trans from said he knows for sure it was good before.


So yeah? i only drove the car about 3 miles with the other ecu, does the Ecu need to "learn" to go into overdrive?

or could it be a bad shift linkage or something?

anyone?
 

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Old thread... yes BUT NO ONE has posted on how they fixed their “overdrive not working issue”.
There are hundreds of posts & no resolution.

Was it a faulty transmission, overdrive solenoid, other solenoid(s), bad ECU, TCU, TPS, ABS, speed sensor(s) odometer circuit board, neutral safety switch, brake light stop switch, dirty tranny filter or screen, kick down button /switch, loose wire, bad ground wire.

MKIV owners who posted “overdrive not working” please post how or what you did to fix “overdrive”

Please reply, I’m desperate!
 

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It’s always something in relation to the ECU not receiving input from sensor(s) to make a decision or sending output after the decision is made.

Could be sensors and/or wiring and/or ECU. If still factory ECU, at this age this I would almost always certainly fault the ECU.

Even if it has been repaired, other components that may not have failed (visibly, physically) yet are outside of values and crazy things happen.

Controlling the J3 A340 is a pain in the dick anyways - why do you think there was only a couple of aftermarket ECU makers that got it to work? Only AEM v2 comes to mind and they struggled with it.
 

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My car did the same thing, but then it worked this year. Check the wiring (although I didn't do anything).
 
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Hey guy's the a340e is not shifting into overdrive.

i thought i might be the transmission so i put a new one in as well as a new differant converter, still has the same exact issue. even put toyota type 4 in it. tried a friends ECU. still act's the same way.

what can i check/do?

TPS set wrong/bad?
Coolant temp sensor? (will be replaced tonight)
Anything else to try? i did the manual test and it say's either a bad ecu (which i tried a new one) or a bad neutral safty switch (the guy i got the trans from said he knows for sure it was good before.


So yeah? i only drove the car about 3 miles with the other ecu, does the Ecu need to "learn" to go into overdrive?

or could it be a bad shift linkage or something?

anyone?
Did you resolve “transmission not going into overdrive?” If yes please share what the problem was and/or how you you fixed it?
 

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It’s always something in relation to the ECU not receiving input from sensor(s) to make a decision or sending output after the decision is made.

Could be sensors and/or wiring and/or ECU. If still factory ECU, at this age this I would almost always certainly fault the ECU.

Even if it has been repaired, other components that may not have failed (visibly, physically) yet are outside of values and crazy things happen.

Controlling the J3 A340 is a pain in the dick anyways - why do you think there was only a couple of aftermarket ECU makers that got it to work? Only AEM v2 comes to mind and they struggled with it.
Please educate me, AEM v2 ? is that a aftermarket ecu? Or do the repair ecu?
 

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It’s always something in relation to the ECU not receiving input from sensor(s) to make a decision or sending output after the decision is made.

Could be sensors and/or wiring and/or ECU. If still factory ECU, at this age this I would almost always certainly fault the ECU.

Even if it has been repaired, other components that may not have failed (visibly, physically) yet are outside of values and crazy things happen.

Controlling the J3 A340 is a pain in the dick anyways - why do you think there was only a couple of aftermarket ECU makers that got it to work? Only AEM v2 comes to mind and they struggled with it.
It’s always something in relation to the ECU not receiving input from sensor(s) to make a decision or sending output after the decision is made.

Could be sensors and/or wiring and/or ECU. If still factory ECU, at this age this I would almost always certainly fault the ECU.

Even if it has been repaired, other components that may not have failed (visibly, physically) yet are outside of values and crazy things happen.

Controlling the J3 A340 is a pain in the dick anyways - why do you think there was only a couple of aftermarket ECU makers that got it to work? Only AEM v2 comes to mind and they struggled with it.
I
I unintentionally fixed my overdrive issue!! It was the diagnostic circuit board (check engine light ABS and the yellow, red oil light ) these lights rarely came on when turning the key to “acc”. I unscrewed the dash, pull it out about 3/4 inches & found a short between the harness & circuit board. I inserted a thick piece of rubber foam under the harness to push it up, now harness & circuitboard are making contact and the check engine, abs, yellow & red oil lights are now working. Pushed dash panel back place in place & turned the key to the ACC & I could hear the ecu making weird clicking & electrical the noises, it was communicating w/diagnostic board. once the chatter stopped i proceeded to start the engine. The engine turned over instantly & sounded completely different!

I knew right then, I fixed it, not sure what I fixed but I fixed something.



Let it warm up & took it for a spin.

I was shocked the OD was engaging, tranny was was shifting into OD with ease @ 45 mph / rpm 1300. (Before the fix 45mph rpm 2300/2500). It’s idling so smooth, it feels so quiet, if that makes any sense?

The real test was to drive it on the freeway & hope the OD won’t drop out.

Holly F**k it accelerated & shifted so quickly w/no OD issues, it made me cry.

It wanted to run & run fast however I don’t drive my Supra over 80mph (ridiculous but true) another weird thing is interior lights, dash lights & headlights are noticeably brighter. I’ve driven it 4 times last month w/ no OD issues.



I didn’t know the diagnostic board would be responsible for all my tranny issues. My focus was on ecu, ect and speedo board, ground wire or transmission.

I have babied my Supra for 23 years and my baby is back!
 

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The legit fix would be to go over the solder joints again. I did this for my car last winter and it helped a little. Not to be pessimistic, just realistic with the experiences I've had - I hope things are fixed for you but I doubt they truly are. I'm still fighting this issue off and on.

 

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The legit fix would be to go over the solder joints again. I did this for my car last winter and it helped a little. Not to be pessimistic, just realistic with the experiences I've had - I hope things are fixed for you but I doubt they truly are. I'm still fighting this issue off and on.

 
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