hey guys 2003 hummer h2 here and i noticed when i go on highway even when theres a small hill it always drops to a lower gear and once it passes the hill, it seems to stay in the lower gear. it seems to have a very aggressive cruise control. i basically have to keep the cruise off because every minute it will drop lower for the smallest hill and then doesnt want to upshift. is there something wrong with my transmission? or is it just a 4l60e thing due to overdrive? hoping to fix if its something easy, i was thinking of just driving in 3 rather then D but then my mileage will be worse. if the road is flat, it is perfectly fine and cruise is golden

thanks!

 

seafoam Trans Tune

 

Also might be some updated software for the PCM but you would need a stealership or someone with a Tech2 and TIS2000 to load any updates. Cannot remember for sure if there was one for the transmission on mine or not (I also have an 03). I know there were a few updates though that corrected certain issues.

 

I never used cruise control for this simple issue. It's a huge completely non-aerodynamic vehicle. Personally would I go through tuning etc, I doubt it. I've had V6s that are underpowered do the exact same thing even with gentle hills. The vehicle will do whatever it takes to maintain the speed you have set.

 

I updated my 2003 PCM software because of a shifting concern that caused 2/3 shift to be laggy causing a clunk in the driveline. My software had never been updated and still had the original programming from 2003. since the update my shift concerns disappeared. but there is a TSB on over oiled after market air filters like K&N style that contaminate the MAF sensor causing shift issues as well. so if you have one of that type air filter that uses oil then try cleaning out the MAF and throttle body. I never checked the cruise control before I updated so I can't tell you definitely off hand if the update is your solution but it might be.

 

You can go to the ACDelcotds site and put the VIN in and see all the calibrations and see if there have been updates, this does not require a subscription.

You can also print all of the data,

input your VIN then select a controller from the list then click next, this will open another page showing the original calibration, look at the top or bottom of the page and you will see a selection for complete history, click this and it will bring up a complete history of all the updates for that controller, you can do this for all the listed controllers on the truck.

You do need someone with a tech2 to pull the calibrations from the truck to see if they have been updated or not.

Neal