Downshifting ? 2005 4x4 DC

Hi guys just purchased a 2005 double cab 4x4 transmission doesn’t want to downshift at highway speeds even if floored. I drained the pan and topped it back up with WS ATF to the proper level. Any suggestions? Thanks.

 

Trans fluid that was removed was a good colour and didn’t smell bad.

 

any codes?

 

No codes or CEL.

 

Otherwise throttle operation seems normal?

 

Throttle operation seems fine but seems to short shift while accelerating as well floored from a stop it’s shifting at about 4500 rpm.

 

Makes it sound like the ECU isn't getting the TPS input the way you are inputting it. Like you're asking for 100% throttle, but you're only getting 65% request to the ECU. Dumb question, what's your floor mat situation? Any chance something is preventing full travel of the accelerator pedal?

 

It has weather tech mats in it I’ll take the drivers side out and take it for a test drive. Thanks.

 

Does it have weather tech mats AND the factory floor mats?

 

Easy to check with the right code reader/monitor.

 

I guess my big question is: Are you ever really truly engaging 5th gear? I’m asking because the OD switch on the 1st gen’s has a penchant for fraying where it enters the shift lever at the column. My thought process is, it’s not downshifting because it’s topping out at 4th gear, because the OD switch is shorting and telling it not to shift.

I know this is a wild ass thought, but I’m just tossing it out there, “you never know”. There (for me) isn’t a huuuge RPM difference from 4th to 5th if I’m just cruising along. Couple hundo RPM, IIRC.

 

Try throttle relearn process and see if that helps.
https://www.tundras.com/threads/throttle-body-cleaning-and-relearning-psa-how-to.121328/

 

Thanks for the help guys. Turns out it was just the floor mats. Truck is pretty quick now and seems to be downshifting as I think it should. They were definitely limiting the throttle quite a bit. What a relief.

 

Glad it was something simple!!