Transmission not disengaging

[D Freeman]

For the 3rd time in the last few months, when I try to slow down, my vehicle tries to keep pushing me through a stop sign. It makes a loud bang, and releases. At no time was I going faster than 50km/hr. Would it be the torque converter at these low speeds?

 

[AVC]

Yeah, that would point to the toque converter lock up clutch pack failing to disengage. Maybe electrical, probably mechanical.

 

[yrwei52]

Yeah, that would point to the toque converter lock up clutch pack failing to disengage. Maybe electrical, probably mechanical.

Agreed. But OP should check possible low ATF level first. And we also need more info on OP’s CX-5, such as model year and mileage ⋯

 

[AVC]

For sure, they should check fluid level, but probably not the issue with lockup *release*. Fluid condition *might* be a factor, where a drain and fill would help. Otherwise, sticking solenoid, clogged oriice, sticking clutch...

 

[D Freeman]

Hi,
Thanks for the reply. It is a 2.5l, 2015 CX-5 with 120K. I have heard that a faulty speed sensor can cause this. It doesn't throw a check engine light...and as far as I know...no codes. There don't to be any other issues like slippage, or bad shifting, shuttering, etc. Just this problem...and about 1/month so it is hard to trouble-shoot.

 

[AVC]

I'll take your word that a speed sensor would cause these symptoms on these vehicles--that would certainly be better than an internal trans issue. A faulty speed sensor usually affects shift points, speedo, odo, braking, set CEL and freeze frame records....

 

[yrwei52]

Hi,
Thanks for the reply. It is a 2.5l, 2015 CX-5 with 120K. I have heard that a faulty speed sensor can cause this. It doesn't throw a check engine light...and as far as I know...no codes. There don't to be any other issues like slippage, or bad shifting, shuttering, etc. Just this problem...and about 1/month so it is hard to trouble-shoot.

I highly doubt your problem is caused by speed sensor. I’d start with the easy one, drain-and-fill ATF and change the filter cartridge although there’s some risk with high mileage transmission at 120K miles unless the ATF has been changed before. If it really is the lock-up clutch problem, the cheapest way to fix is to get a used transmission.

 

[D Freeman]

Took the car to the dealership today...and there is apparently a TSB called "High Engine Idle Speed When Stopped In Drive". I guess it can cause lurching. Although I was stopping (not stopped), they assured me that it applies to my condition as well. Time will tell. They updated my PCM and sent me on my way.

 

[Ronzuki]

they assured me that it applies to my condition as well. Time will tell. They updated my PCM and sent me on my way.

Now they can't sell as many pre-mature brake jobs that only properly equipped dealers can now do, damn...busted.

 

[erhayes]

Glad the dealer stepped up and fixed it. Some shops play dumb about TSBs. Ed

 

[yrwei52]

Glad the dealer stepped up and fixed it. Some shops play dumb about TSBs. Ed

Provided that the Mazda dealer didn’t charge him for PCM update based on the TSB for an out-of-warranty vehicle.

 

[AVC]

Did they comment on the "bang"? Just an awkward torque converter release due to a confused PCM? Did you get a copy of the TSB full text?

 

[Avoidin Deer]

Now they can't sell as many pre-mature brake jobs that only properly equipped dealers can now do, damn...busted.

And their cousin Vinnie the chiropractor is gonna have to tone down his kids' Christmas this year.

 

[yrwei52]

Took the car to the dealership today...and there is apparently a TSB called "High Engine Idle Speed When Stopped In Drive". I guess it can cause lurching. Although I was stopping (not stopped), they assured me that it applies to my condition as well. Time will tell. They updated my PCM and sent me on my way.

Can you tell if the PCM update has actually fixed the problem you had?

 

[AVC]

And, what color paper was the TSB on? Kidding....

 

[yrwei52]

Can you tell if the PCM update has actually fixed the problem you had?

The reason I asked is because the description in the TSB doesn’t seem to match your transmission problem, especially “these conditions may occur when the customer depresses the brake pedal and makes contact with the throttle pedal simultaneously.”

Nevertheless getting a newer version of PCM firmware is always a good thing, especially if you got it for free.

Subject: HIGH ENGINE IDLE SPEED WHEN STOPPED IN DRIVE
⋯
DESCRIPTION
Some customers may complain about one of the following symptoms when the vehicle is stopped and the transmission is in D range:
• An intermittent high engine idle speed.
• An intermittent engagement shock.
• An intermittent forward lurch.
These conditions may occur when the customer depresses the brake pedal and makes contact with the throttle pedal simultaneously.
Customers having this concern should have their vehicle repaired using the following repair procedure.

 

[Ronzuki]

The reason I asked is because the description in the TSB doesn’t seem to match your transmission problem, especially “these conditions may occur when the customer depresses the brake pedal and makes contact with the throttle pedal simultaneously.”

Nevertheless getting a newer version of PCM firmware is always a good thing, especially if you got it for free.

Unless, of course, it 'fixes' something that wasn't broken in the first place.... which never happens...

 

[AVC]

Or the stated "reason" is the lawyer's CYA language, so they don't get sued because of unintended acceleration caused by the *vehicle* rather than the driver.

I have noticed my '17 has some slight drivetrain bumps after coming to a stop (assume it's a shift from 2nd to 1st) and a similar bump passing through ~10 mph (assume torque converter lockup). It also has a slight idle speed hike upon releasing the brake, which I'm guessing is part of the hill hold feature. Certainly as busier arrangement than my Highlander had.

 

[Avoidin Deer]

Or the stated "reason" is the lawyer's CYA language, so they don't get sued because of unintended acceleration caused by the *vehicle* rather than the driver.

I have noticed my '17 has some slight drivetrain bumps after coming to a stop (assume it's a shift from 2nd to 1st) and a similar bump passing through ~10 mph (assume torque converter lockup). It also has a slight idle speed hike upon releasing the brake, which I'm guessing is part of the hill hold feature. Certainly as busier arrangement than my Highlander had.

Stupid question: Have you checked yur transmission fluid? Lots of folks report that as being low from the factory. And it's not as convenient as checking the oil, so it rarely gets looked at.

 

[D Freeman]

The reason I asked is because the description in the TSB doesn’t seem to match your transmission problem, especially “these conditions may occur when the customer depresses the brake pedal and makes contact with the throttle pedal simultaneously.”

Nevertheless getting a newer version of PCM firmware is always a good thing, especially if you got it for free.

The TSB is 01-14-08...and I've seen that description on similar TSBs. I'll let this thread know in a few weeks when we get some time with the repair. This was/is such an intermittent issue...with only 3 events happening since November. If I can get through March without an incident...then I'll consider it fixed.