Random no upshift issue...Anyone else? 2017 CX-5

[Joebrick]

We have a 2017 Mazda CX-5 with 73,000 miles. Recently the transmission has very randomly failed to upshift. Once at highway speeds it resolved itself and once in 1st gear it wouldnt upshift to 2nd. Stopped the car, let it sit and then it was fine. Has anyone seen or heard of something like this?

I thought it might be fluid since my "lifetime fluid" hasnt been changed but it doesn't seem consistent enough to be dirty fluid. I have pulled the battery cable to reset the system and we'll see what happens. All is well for right now. No codes or check engine light throughout. Anyone else seen something like this?

 

[ceric]

I recommend a ATF drain-n-refill at least.

 

[N7turbo]

I recommend a ATF drain-n-refill at least.

And maybe a transmission reset. Disconnecting the battery won't do it.

 

[Lazy2.5]

What you're experiencing is inconsistent because contaminated fluid is beginning to wear our your solenoids and valve-body.

As always. Strainer(Filter), fluid replacement. Reset the transmission. Mazda Skyactiv AT initial learning mode. #skyactiv #mazda #automatictransmission

If your solenoids are worn, doing the reset will not permanently resolve your issue.

Unless there is some mild transmission defect, I would suspect that your transmission is used in a "spirited" manner if your solenoids are acting up at this mileage, although just the dirty fluid is enough to be causing you issues at this point.

Act now and call a transmission shop before it gets worse.

 

[yrwei52]

I recommend a ATF drain-n-refill at least.

OP’s problem could also be caused by low ATF level from factory which has been verified by many members here. Before he does an ATF drain&fill, OP should check ATF level at proper ATF temperature (122°F) with engine idling.

 

[Lazy2.5]

OP’s problem could also be caused by low ATF level from factory which has been verified by many members here. Before he does an ATF drain&fill, OP should check ATF level at proper ATF temperature (122°F) with engine idling.

so a low fluid issue could become apparent at higher mileage?

 

[yrwei52]

so a low fluid issue could become apparent at higher mileage?

The modern automatic is very complicated and the TCM software controls plenty of components depending on many collected data. For example the TCM custom-matched and controls all direct linear solenoids that have flow rates that vary between solenoid.

When the fresh ATF is low, it’s within the tolerance where the software is able to make sure every component can function properly. When the transmission gets higher melange and the ATF gets contaminated with changed characteristics, that could be out of tolerance under software control with low ATF level.

Of course this’s just my guess. Besides, checking the ATF level and making some ATF change follow by a real ATF reset mentioned above are the least expensive steps the OP can do at this point. All other options would cost OP an arm and a leg.

2024 CX-5 TCM / Transmission Failure

Sorry I am multitasking poorly right now lol.
To get the TCM from Mazda you need to order the entire "mechatronics" unit. It goes by a few names depending on who you are talking to but can be called a valve body, mechatronics unit, Mazda lists it as "Valve, Control" in most of the parts catalogs. It consists of a traditional valve body including solenoids, wiring harness and TCM. Mazda sells it as an entire unit because it uses direct linear solenoids that have flow rates that vary between solenoid. When Mazda produces the valve bodies they flow each solenoid to each valve body and write that information into the TCM so it can correctly control each solenoid. First picture is the whole unit, second picture is the TCM portion and then third is the solenoids.

Mazda will sell you the valve body separate from a new transmission, my reply should have read that I've ordered the mechatronics assemblies.