Reading "Live Data Stream" from an 08 Yukon xl 2500 6.0l

[GO0BER]

Hey all,

I just bought a 'new to me' 2008 Yukon XL 2500.. On the day I went to look at the truck I had a $35 scan tool and was poking around looking for CEL or other errors and found none.. Overall truck looked great so I bought it and brought it home.

Fast forward 5-6 weeks and I now have access to an Autel MaxiCOM mk808 scanner and I wanted to get a better look at the vehicle and how its running. There are a few values that are displaying that I don't quite understand and I have tried googling for a bit and can't seem to find the correct key-words for what I am looking at.

In the 'live data stream' I can see values such as Engine speed, calculated throttle position, tow mode activation, command gear, and more..

2 values in this list that don't make sense to me are the "ENGINE TORQUE" (units are in Nm, range should be 0 - 510.. my values at idle are actually negative) and "GEAR RATIO" (range shows 0-5, my actual value is 8 at idle)

While driving these seem to fall in with the values, when my engine speed is at 1300 my torque shows 170.. and my gear ratio will move to values like 1.15 or 0.85(though when my gear ratio changes.. my engine speed/torque are blank?)

What exactly should I expect to see in these fields?

I will attempt to get screen shots from the device to post ASAP.

 

[Mikey52]

The torque is a computed torque, not actual. So idling in park it should be close to zero. Not sure about the ratio, unless it's trying to compute the final drive ratio by taking into account tire size, transmission gear and rear end drive ratio.

 

[Dean E]

I had purchased an Autel MK808 tablet but when I found out it was not bi directional I turned it back into Amazon. Autel does have a decent tech line that you can call or email. They might be able to give you more details to your questions. Dean

 

[KyleC4]

Gear ratio is a figured determined when comparing input an output speed sensor signals. This is how your tcm knows when it commands 3rd gear it actually is getting 3rd gear. 1st gear = 4:1, 2nd gear = 2.4:1, 3rd gear = 1.5:1, 4th gear 1.1:1, 5th .8:1, 6th .6:1. Those are approx figures you’d see. Should be a 6L90 in that thing. Engine torque I believe is one of the signals used for the torque management software and shift strategy. And yes at idle in gear or in park I’ve seen gear ratio data show 0, 8, etc.

 

[GO0BER]

Hey all, sorry for delayed response.. My daughters softball schedule is pretty intense right now..

The torque is a computed torque, not actual. So idling in park it should be close to zero. Not sure about the ratio, unless it's trying to compute the final drive ratio by taking into account tire size, transmission gear and rear end drive ratio.

I kind of assumed this was the case.. but having never seen it (or even having access to see it) on a scanner, it was a bit weird.. I am still confused as to why it would be showing a negative value.. I wonder if I have a sensor that is acting a bit wonky?

Gear ratio is a figured determined when comparing input an output speed sensor signals. This is how your tcm knows when it commands 3rd gear it actually is getting 3rd gear. 1st gear = 4:1, 2nd gear = 2.4:1, 3rd gear = 1.5:1, 4th gear 1.1:1, 5th .8:1, 6th .6:1. Those are approx figures you’d see. Should be a 6L90 in that thing. Engine torque I believe is one of the signals used for the torque management software and shift strategy. And yes at idle in gear or in park I’ve seen gear ratio data show 0, 8, etc.

so seeing an 8 in park is not unheard of? PHEW! That is good news.. I was worried I was going to have to get inside of it for a sensor or something.. Not what I want to do in the near future (also.. I meant to state mine showed 8 in partk.. not at idle.. I am silly)