Tcu? Does it matter?

skipnrocks · Nov 21, 2015

So I have a 4l80e with an eztcu and I wired it to a speed sensor on the atlas. I am getting some funky readings and am not sure if this is why. So I called the tech line and he acted like it was weird that I used the tcase sensor. I said it's because it spends most of its time in four wheel drive and he didn't really say much. So my question is if I hook it to transmission and get s normal reading do I get s new tcase speed sensor? Or just leave it? And if I leave it doesn't it mess with my shift points in 4x4 mode?

In my head it tells me it's always going to upshift too early if I'm always in low or ultra low? Is this bad logic?

doubleud · Nov 21, 2015

You really probably should be getting your speed sensor reading from before the transfer case. If its reading the output shaft coming out if the transfer case that will mess up your shift points. It needs to shift earlier when in low range. Factory ECM's use a low range input to change the shift points when in low range.

An example would be going 30mph in 1st gear high range, but you'd over rev the engine trying to go 30mph in 1st gear low range. So you'd need to upshift sooner in low range.