# Auto Tranny since service



## Patman (May 7, 2011)

Well on #7 2016 RS with 70K. Shortly after I bought it, I had the tranny serviced(flush and fill) @ 50K I notice now going down hills, if I am not in the throttle I hear the engine/tranny holding the car back and not upshifting. Since I am genneraly not used to driving an auto is that normal as I have never had a tranny serviced before and did not notice if it did that before. I noticed if I am in the throttle sometimes it seems to shift later(would that just be the RS functioning)?


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## Booger (Oct 18, 2020)

Did you check the transmission fluid level?
Was the fluid change done with the appropriate fluid?
Are you sure that the TPS sensor is working correctly? I would check it with an OBDII reader that does live data, and this would be the first thing that I would do too since it's the easiest.


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## Thebigzeus (Dec 2, 2018)

Do you mean its staying revved up a bit even though you’re off the pedal? Mine does this, but I thought it was the BNR trans tune keeping the turbo spooled...


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## zr1000a1 (Jan 25, 2012)

It's called automatic grade braking:








GM 6-Speed 6T40 MH8/MHB Hydra-Matic Automatic Transmission


The Hydra-Matic 6T40 (production code MH8/MHB) is a six-speed automatic transmission produced by General Motors for use in front-wheel-drive vehicles with a transverse powertrain orientation. Developed in-house by General Motors,[...]




gmauthority.com




..."
*Adaptive Shift Controls*
Adaptive shift controls include automatic grade braking, which commands the transmission to remain in a lower gear if the vehicle is decelerating or coasting on a downgrade. This takes advantage of engine braking to prevent unwanted acceleration. This reduces the number of brake applies for the driver to brake during a hill descent. The control module receives input that monitors brake pedal usage, vehicle acceleration rate, throttle position, and even whether a trailer is connected to the vehicle."...


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