Flashing S sign

Welcome back. The flashing Sport Mode light means there is a fault code stored in the transmission control computer. The way to determine what the code is requires a scan tool to pull the code.

That sounds like there is a failure in the transmission control module and not a mechanical failure. There should be a specific code stored that a scan tool can read and allow you to test the system. Testing by a transmission shop would be the next step unless you have the proper pressure gauges and specific charts to match that engine/transmission set up. That allows for testing of the transmission selector and the solenoids that control the transmission.

Shaking isn't a good sign, it can indicate internal parts failure, however if the control module isn't sending the proper application commands it could also be from low pressure or poor clutch apply control. Testing the transmission is the only way to determine the problem. It's also possible it is a combination of problems.

You are welcome. Please return any time with your automotive questions.

Check to see if the fan is coming on and possibly staying on. Also look to be sure none of the wiring around the trans was damaged. A short can cause a lot of problems. Also check to be sure the torque converter isn't staying locked, a way to do that would be to shift to neutral when you stop. If the engine stays running then it's possible the converter is not releasing.