PTO mode and the 4L80E trans

[jeffreydmet]

Does anyone know how PTO mode affects the function of the 4L80E transmission? I am wondering if it could be exploited to make the transmission behave better in certain situations.

[Chris Hinds]

I can't speak to the 4L80, but on my '96 with a 5-speed, PTO mode (High Idle) is disengaged if the ECM sees brake, clutch, or more than about 3mph.

If you're looking to have a higher idle speed when you're not moving, it might work, but as soon as you get above 3mph or whack the brake pedal, it'll probably fail out just like the man trans version.

C

[CareyWeber]

On my 97 with the 4L80E if you touch the brake, or put the truck in gear it disables the pto idle speed control.

Carey

[Cowracer]

Funny, with the Heath chip in my truck, my computer does not kick out of high idle when I brake or put it into gear.

I actually find this usefull at certian times, such as backing a trailer up a hill or pulling the boat out on a slick ramp. I use the brakes to control speed, and just let the engine (high) idle.

Tim

[jeffreydmet]

What I was wondering about was how the gears and TCC are handled with the pto mode on. I noticed on my truck the pto is connected out of the transfer case. That means that the transmission would have to be in gear to be able to use it. Also I would think there are applications such as salt spreaders dump trucks or fertilizer spreaders that would require the pto while the truck is moving. Just think there may be a way here to gain some more control over the trans.