Hyundai Repair: transmission trouble, hyundai elantra, pulse generators

Question
QUESTION: I have a 1996 Hyundai Elantra, automatic transmission 1.8 engine.  When you try to go it jumps in and out of gear, once you are moving it shifts fine, it is only on takeoff or when you have to come to a stop. At first it would only do it in drive, you could take off from low gear ok, but now it is from any gear, except reverse. What could the problem be?

ANSWER: The most likely circumstance is that the transmission needs to be overhauled or replaced, but there are a few simpler (although less common) items to check:

1.  Fluid level-- low fluid can cause this issue.
2.  Pulse generators-- malfunctioning pulse generators can cause abnormal shifting and operation.
3.  Range switch-- a shorted rain stitch will be manual.

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QUESTION: Where are 2 and 3 located? Have never heard of them before. Thanks

Answer
The pulse generators are located in the case of the transmission.  One is approximately under the brake master cylinder and the other is in the bottom front of the end case.  The range switch (not "rain stitch" as I seem to have typed above) is located under the shift lever on top of the transmission.

Realistically, you won't be able to test the pulse generators reliably without a scan tool.  The best you'll be able to do is probably to make sure the wiring going to them isn't broken.  The range switch output can similarly be checked with a scan tool, but you'd also be able to test it with a voltmeter by monitoring the output of each circuit in each gear position.