In my mom's GLE auto, when it shifts from 1st to 2nd there's a sharp yank of the car forward. What the hell is that from?

 

Is it cold outside when it does this? If so the trans is probable still warming up.

 

It is cold now, but usually does it when it's not cold also

 

How many miles are on the car?
When was the last time the tranny fluid was changed?

When the tranny is cold, the 1st to 2nd shift is a bit harsh, thats normal. Once it's warmed up it becomes a slush box.

If your getting hard shifts when the tranny is warm, the dropping resistor may be at fault. Have a local tranny shop take the car for a drive and give you their opinion.

Make sure the fluid is clean and up to the correct level.

 

The fluid seems to be fine. She'll probably have to take it in. It's got like 130,000 miles on it, But she got a new transmition around like 105 I think. My uncle (owns a dealership) seems to think it's got something to do with some belt being to tight.. ??