Transmission wont lock TC when using cruise contro

[Dave424]

Car: 2010 Mazda 6, 2.5L 5AT-uses Mercon V fluid

When driving at hwy speeds, TC locks up just fine when not using the cruise control regardless of weather going on flat level road or with a slight grade. However, TC will unlock and RPMs jump by about 200-300 as soon as I engage the cruise control. I have called Mazda dealers and none of them seem to know why. I am concerned that it may generate extra unnecessary heat that can cook the fluid and damage the trans, as well as reduced fuel economy.

 

[supton]

Is it fully warmed up, and traveling fast enough?

Sorry, can't think of anything else.

 

[95busa]

Does it lock back up?

 

[eljefino]

That's pretty annoying. Is it throttle by wire or do you have a cable?

I wonder if something in the computer system like a TPS is going screwy when it enters a different mode for cruise mode.

 

[NHGUY]

With todays electronics,it probably needs a reflash...

 

[Kuato]

Originally Posted By: 95busa
Does it lock back up?


My thought also; I've had a couple rentals that unlocked when you engaged and then the TC locked up a few moments later. Neither were Mazdas though.

 

[Dave424]

Nope, it will unlock and stay unlocked until either, cruise control is turn off, increase speed to 70 or keep it between 40-50. So between 50-70 cruising speeds it will lock up just fine, as long as i don't use CC. I found a thread on a mazda forum with similar issues, and the dealer agreed that this is strange but did not know what to do...

 

[2oldtommy]

Dave, The 5AT in your 2010 mazda6 does not use Mercon V fluid. It requires Mazda M V (or M5) atf. This is confusing to Mazda owners. Check out the Mazda forums for confirmation of this. I don't know if you changed your atf, but please use the correct Mazda M-V atf. Ford also has a special P/N for this fluid as they used it for certain models. FWIW

Oldtommy