So the a340e has two speed sensors. One sensor looks like VSS1 but it’s used to measure the forward drum speed. That one is further toward the front of the trans.
They look like cam position sensors.
The deal is though, and I may have this backwards, VSS1 is considered the primary speed sensor, it runs through the odometer circuit and it’s signal (waveform) is smoothed out using a buffer circuit to feed a clean signal to the ECU, if VSS1 fails, it will use VSS2 as a backup, which is a sensor that is opposite side of VSS1, both are toward the back but #2 has a plastic gear that turns a shaft that slides in to VSS2.
The drum speed sensor and VSS1 look the same.
If you have the code for one of them, replace it, they used to be expensive but you can get AISIN branded speed sensors on Amazon and EBay cheap now.
You can have a bad odometer and/or bad solder joints in the odometer and it still count miles and your speedo be off. That is why a lot of people bypass the odo buffer circuit to just send the signal straight from the trans to the ECU.
From your other threads, you likely have one or more problems, it looks like you have at least one bad VSS and a jacked up ECU too. Very common.
When my ECU was failing, sometimes I would be going 60 or 70 and it would be stuck at 35mph. Even when I stopped at a light it would slowly creep down. I couldn’t pull codes from it, AC was all stupid, cruise wouldn’t engage, idled like a fuel rich race car, various other stupid things and etc.
Last but not least, the capacitors can also fail in the speedo cluster too. Search for posts by Stu Hagen - you will learn a lot from those.
In the end, I have a functional vehicle, reliable as hell but I still have weird shifting problems. Even after the ECU rebuild, full sensor and connector replacement, my car will gear search while going down the road, shifts at 3500 rpm in every gear, won’t hold manual selected 1st, it auto shifts in to 2nd. Driving it like a good normal car, you never know, it’s just when I want to show out it gets stupid. But I have no codes, speedo is right, trac and manu work. Just don’t expect a full throttle downshift.
The a340e transmission control is janky as hell and if one thing is off it will screw up.
I’m going to do like others and go stand alone when I get the time. AEM has one that will control the a340e stock crapbox.