Hyundai Repair: trouble codes p0734 andp1624, transmission control module tcm, transmission control module

Question
My check engine codes revealed a p0734 transmission code indicating the following: a 4th gear incorrect ratio problem due due  either open or short circuit, faulty pressure solenoid, or internal transmission failure. The other code (p1634 indicated a low cooling relay circuit fault due to either an open or short circuit, poor electrical connection or bad fan relay. I did notice that the fan blade is really lose and it looks like either the motor has been replace or maybe the sensor located on the right side of the radiator. What does this motor do, does it run while the car is running or is it the one that kicks on after it is turned off. Could this be a contributing cause to the transmission cooling ability, causing the transmission to overheat? Tim

Answer
I'm presuming you have code P1624 as indicated in the subject, not P1634 as indicated in the text.

P0734 basically indicates that your transmission is slipping.  P1624 is simply a marker in the engine control module (ECM) that your transmission control module (TCM) has requested the check engine lamp to be turned on.  It has nothing to do with the radiator fan or a cooling relay.

The bad news is that you probably have a serious transmission problem that will require a transmission overhaul or replacement.  Considering the expense of repairs involved, I'd recommend taking the car to be checked professionally.  In this case, I'd recommend taking it to your local dealer.  I've found that aftermarket transmission shops tend to like to sell overhauls when they're not needed.

Your radiator fan is controlled by your ECM based on coolant temperature.  It can operate any time the engine is running, but the ECM will only turn it on when the coolant temperature is high enough to justify the fan's use.