Hyundai Repair: 2002 Hyundai Accent Transmission, hyundai accent, transmission replacement

Question
Hello. I have a 2002 Hyundai Accent GS with an automatic transmission (1.6L engine). The trans was replaced at 65K miles by the dealer due to a "catastrophic internal failure". Let's just say it slammed into lower gear when accelerating. I am now at 127K miles with routine maintenance completed as required. I am now faced with another transmission problem. The dealer scanned and reported a P1709 code which I believe is a neutral / park switch out of range code. The dealer also claims this is an internal problem and the transmission needs to be replaced...again. The service agent stated that the switch was open shorted. I didn't bother to say "well which is it, open or shorted". I asked if the switch can be replaced and was informed it is internal calling for entire transmission replacement. I am not getting the warm fuzzy here and would like to know more about the switch and if it can be replaced without dropping the trans. The current symptom occurs after the car has be driven for awhile(hot). The trans does not down-shift properly at a stop. There is a long delay to shift sometimes not shifting at all. When I accelerate the trans will will clunk into gear. Please advise. Thanks.

Answer
P1709 means that the computer believes the kickdown servo switch to be open or shorted.  That's probably why you received the "open or shorted" explanation from the service agent.  

While it's possible the problem is in the servo switch or the wiring, most cases involve an internal transmission problem.  If there is insufficient pressure to activate the kickdown servo, the transmission computer sees this as a kickdown servo switch issue.

While the kickdown servo switch can be replaced with a small amount of effort, the failure is almost always internal in the transmission.  Furthermore, your symptoms tend are consistent with a kickdown servo pressure issue rather than an issue with the servo switch.  The likelihood is great that the dealer is correct in their assessment of the problem.