Transmission Hard to Shift in Wet Weather - MAF Sensor Fix

[skyak]

Posting in case any others run into this issue.

We had shifting problems to/from Park/Reverse/Drive on our LC200 after bouts of wet weather. The transmission was very hard to shift. I could make it easier by manually increasing the idle while shifting. Vehicle has about 70k miles on it. I read somewhere that this could be caused by a dirty MAF air sensor. I bought some cleaner and gave the sensor a good cleaning. I also cleaned the throttle body at the same time while I was at it.

Happy to report that the issue seems to have been completely eliminated. It has been over 6 months since the fix.

 

[KLF]

Ok, how the heck can the MAF have anything to do with shifting the transmission?

Windows slow to roll up? Check your brake fluid!

 

[skyak]

Ya it's weird, the complete correlation with wet weather is what made me think it was something sensor related. Guessing the computer uses MAF readings to do something which was causing transmission flow/pressure issues??

From somewhere online: "Most transmission control modules use inputs from other sensors on the vehicle. If a vehicle can’t accurately calculate the load on the engine, it will adjust the line pressure and slippage to the inaccurate calculation. Sensors used to calculate the load can include the Manifold Air Pressure (MAP), Mass Airflow Sensor (MAF) and Throttle Position Sensor (TPS)."

 

[cboyd]

I have this problem on my 2015 and can confirm I have had this issue more in wet weather than in other types. In fact, I had the most severe case of this after driving in some storms with slightly flooded roadways... interesting correlation indeed. The other time I have it is after the vehicle sits for a week (Like at the airport). I”ll have to try the idle up trick to see if that eases the shift on my return from the current biz trip.

 

[razzyrazz]

This has been bothering me for a while at 90k miles now on my 2011 LX. Thinking about it now it seems like wet weather may be the constant. Have no other symptoms that would point toward a trans fluid issue so will try this ASAP. Thanks.

 

[ytaebnairb]

Posting in case any others run into this issue.

We had shifting problems to/from Park/Reverse/Drive on our LC200 after bouts of wet weather. The transmission was very hard to shift. I could make it easier by manually increasing the idle while shifting. Vehicle has about 70k miles on it. I read somewhere that this could be caused by a dirty MAF air sensor. I bought some cleaner and gave the sensor a good cleaning. I also cleaned the throttle body at the same time while I was at it.

Happy to report that the issue seems to have been completely eliminated. It has been over 6 months since the fix.

I have made the same correlation to wet weather and sticky shift, but I also do not see how the MAF would cause this. I am going to give it a try though next time. I was almost ready to swap out the NSS (Neutral Safety Switch) to address the issue. The computer and sensor link scenario is plausible for sure, just not sure how it would adjust transmission fluid pressure? I will give it a try and report back here. Thank you!

 

[cboyd]

I can confirm that when I got back to truck last night, that it was sticky from sitting for a few days at the airport as usual. I idled up a bit more than the initial fast idle the truck normally does and it was easier to shift. I let it idle back to normal and it was stiffer.

To me that makes sense, because maybe the transmission fluid pressure is higher. I was previously correlating the wet weather to stuff getting up the linkage of the shifter, but now I can see that it might be a sensor issue. I was struggling to figure out why it did it after sitting in garage all week....

FWIW, Once in a blue moon I also get a CDL warning, which I have read is related to low trans fluid temps.. if I shut the truck down and restart it would go away immediately. I wonder if this is also related.

 

[skyak]

Interesting to hear from others that our experience was not an isolated case. I would love to understand what is actually happening.