5-speed A750 trans won't shift in to 5th gear. (2 Viewers)

[hoser]

Try asking Orto.

Ask Orto - Technical Questions and Answers

Orto is our resident technical automatic transmission expert.

automatictransmission.com.au

 

[MongooseGA]

Try asking Orto.

Ask Orto - Technical Questions and Answers

Orto is our resident technical automatic transmission expert.

automatictransmission.com.au

Worth a shot. I sent them a message.

 

[LJE]

I'm not sure how they compare. The ScanGauge, to my knowledge, should read any codes that come up in real time. But maybe there's another layer of diagnostics that isn't read through the OBD port?



I don't have TechStream. But I have found something here about jumping ports on the diagnostic module (in the engine bay I believe?) to trigger light flashing on the cluster sort of like OBD1 would have done.

FWIW, I've seen stored codes via Techstream that won't pull up with my generic Bluetooth OBDII reader, likely for the reason @Bisho states.
I'm looking through the diagnostic manual now - I'll post some pictures of the pages here in a minute if I find anything of note.

 

[LJE]

A lot of these procedures relate to solenoids, which I feel like you (most likely) ruled out when you swapped transmissions.ill look in the traction control section and see if I can find anything related to it being able to disable 5th gear - according to the transmission section, that's not a factor.

 

[LJE]

Here's some more... Couple more images after this. 11 month is awake now though, so will be wrangling her for a while.

 

[LJE]

Last two for the moment.

 

[MongooseGA]

A lot of these procedures relate to solenoids, which I feel like you (most likely) ruled out when you swapped transmissions.ill look in the traction control section and see if I can find anything related to it being able to disable 5th gear - according to the transmission section, that's not a factor.

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Super helpful, thank you! I will send this to the shop. I'm not sure if they'll have Toyota specific diagnostic tools but worth a shot. I imagine this may need to go to the dealer soon.

Ugh...

 

[LJE]

Super helpful, thank you! I will send this to the shop. I'm not sure if they'll have Toyota specific diagnostic tools but worth a shot. I imagine this may need to go to the dealer soon.

Ugh...

For sure. Apologies for the odd mix of portrait and landscape - wasn't paying enough attention to how my phone thought it was oriented.

It looks like I also missed page DI-249 - see attached.

 

[LJE]

OK, dug through the (lengthy) ABS/TRAC/VSC section. I couldn't find anything that stated it would disable 5th gear in any fault condition.

I had a thought - while swapping transmissions should have eliminated any issues with the solenoids themselves, it wouldn't have eliminated any issues in the wiring between the ECM and the
solenoids (or an issue at the ECM itself).

Looking at DI-285 (reattached here for ease), if you had an issue with the solenoid SR (right hand column), or the wiring going to SR, you'd lose 5th gear, but it'd be able to use the other solenoids for 1->4th.
If you were having issues with the other solenoids, it'd be able to compensate (which is pretty cool!) to keep 5th.

I've also attached the pages related to checking the wiring and ECM for the SR solenoid and the TC lockup solenoid.

 

[MongooseGA]

Dude, thank you so much for this! The tech has mentioned the possibility of a break or failure in any of the wiring or connectors and was going to start looking through that on Monday. I will send this along to him.

 

[LJE]

Dude, thank you so much for this! The tech has mentioned the possibility of a break or failure in any of the wiring or connectors and was going to start looking through that on Monday. I will send this along to him.

I also want to highlight that with tech stream (or a sufficiently advanced handheld reader), you should be able to manually choose the gear and lock the TC via the active test section.

$30 and the 'Techstream in 5 minutes' thread would get ya set up: https://www.amazon.com/dp/B07JYSPBG...WXXVJV1C9JQWXY328&starsLeft=1&skipTwisterOG=1

 

[2001LC]

Back to water temperature circuit. We must have 133F (IIRC), signal to ECT module.
Second; shift handle circuit D (5th) to 4th is electronic overdrive SW.

 

[97 AZ LC]

To Techstream in 5 minutes you must first read "TechStream in 5 Minutes", which takes about a hundred hours.

 

[LJE]

To Techstream in 5 minutes you must first read "TechStream in 5 Minutes", which takes about a hundred hours.

Hahaha - you're not entirely wrong. If it works right the first time it's easy... If not, it can get annoying quick.

The hard part is all the adaptors look the same, but not all actually work. People that have bought the adaptor I linked seem to have pretty good luck with the VM image in that thread.

 

[MongooseGA]

I'll dig in to it. I've thus far been able to get along without it.

 

[Patron100LC]

Your transmission shop has to have a bi-directional scanner, you can’t do a job on a modern car without it.
The question is if they know how to use it.
If they’re old school, they’ll learn what they have to use every day and not investigate anything else, that’s how our mind works when older..

I’ll disassemble your transmission for free if it saves me from downloading techstream again.

 

[MongooseGA]

Try asking Orto.

Ask Orto - Technical Questions and Answers

Orto is our resident technical automatic transmission expert.

automatictransmission.com.au

This is what I heard back from them:

Hey buddy, thank you for your inquiry.



We would suggest putting a scan tool on the vehicle and seeing if the TCM is commanding 5th gear, if it isn’t commanding 5th gear we recommend clearing any other codes the vehicle may have (transmission related or not) as these can also cause this to happen.



If the issue persists then you may have a faulty TCM



Cheers

What's so odd is that there are still no codes showing. Patch is going to loan me his tech steam laptop to dig in to this further. I also have a "transmission relay controlmodule" on order, which is all I can find when searching TCM (besides the ABS/TRAC/VSC module, also on order).

 

[LJE]

This is what I heard back from them:



What's so odd is that there are still no codes showing. Patch is going to loan me his tech steam laptop to dig in to this further. I also have a "transmission relay controlmodule" on order, which is all I can find when searching TCM (besides the ABS/TRAC/VSC module, also on order).

Hmmm. The wire harness that runs to the transmission comes straight from the ECM. Pretty sure the ECM does all the control stuff for the transmission in a 100 series - looks like the 80 series had a separate TCM.

 

[Malleus]

Correct.

 

[MongooseGA]

I got some news!

@cruiserpatch loaned me his TechStream laptop today and I was able to hook it up to the truck.

First thing I checked were the ABS/VSC/TRAC systems. It gave me the following codes:

So I cleared the codes and took the truck out for a drive. First thing I noticed leaving the parking lot, it slams in to first gear when decelerating. Not great. Upshifts were smooth like they should be, but no shift to 5th. I played with the gear lever, going from D to 4 and back. There's a tiny but noticeable attempt to do something when it wants to go to 5th. A teeny adjustment in revs and just the slightest little hiccup can be felt through the trans. Oh, and it will downshift now with a jab of the throttle, although it does kind of clunk in to lower gear sort of harshly.

OK, so went back to the shop and looked to see if codes returned. They did not. (Should mention, none of the 3 idiot lights ever came on during my driving today). Good news. Also decided to look at the Engine and ECT section for codes, and whamalamabambam, here she is!

So that's referring to a specific solenoid. When the tech initially dropped the old pan and tested the solenoids, he did so by applying 12v to them and observing on/off function. Thanks to the docs posted by @LJE , we found the proper test procedure includes testing resistance, not just operation. So, they're going to likely drop the pan again today and fully test the necessary solenoids.

Finger crossed with stuff.

I have the ABS/TRAC/VSC module and a transmission control relay incoming.