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Old 12-30-2013, 11:24 PM
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Default Cold Weather shifting issues

theres a similar thread about this. it's the programming. I believe something to do with the fluid being so thick at that temp, it bungs things up and burns up torque convertors.

Edit: here's a quote from it:

"Starting in 2010 MY, we made a change to the transmission control logic / calibration, that delays the 2-3 upshift whenever ambient temp (not sump temp) is below -15°F (below -26°C).

The reason is to prevent torque converter failures (due to overheating) in the event that the trans oil cooler becomes "frozen" at low temps. Transmission fluid can become very thick at low temps, effectively blocking flow through the cooler. This then can lead to the converter overheating (due to lack of cooler flow). When we hold 2nd gear longer (by delaying the 2-3 upshift), it reduces the amount of slippage (and therefore, heat generation) in the converter, thereby avoiding the converter overheat.

In these trucks, the trans oil cooler is oil-to-air (it's not inside the radiator bottom tank), so as long as the ambient temp stays low, the cooler flow may remain restricted. That's why the 2-3 upshift delay is tied to the ambient temp, rather than the trans sump temp or engine coolant temp."

Last edited by smurfs; 12-30-2013 at 11:28 PM.
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