there isn't one, there are two plugs in the transmission pan, one drain plug and a fill plug. a great site for info on this and other vw questions is www.passatworld.com
click on forums then b5 (that's your car) and there is a thread in the information forum that tells you how to check/change Transmission Fluid and filter. i followed the instructions its straightforward, always use vw spec fluid.
it doesnt have one vw thought that the trany fluid would never need to be changed
how to remove oil pump for 99 vw passat.
There is a diPstick at the front on the transmission differential
How much it cost to put a transmission in a 1999 passat
6 liters.
If it is an automatic, the fluid should be at operating temperature. The transmission in park and the engine at idle. Remove the dipstick and wipe it dry and check the level. Do not overfill.
take the bulb out
transmission fluid almost always goes in the dipstick tube
The transmission control module on a VW Passat from 1999 is located under the passenger side floor carpet. The TCM gather input from sensors to implement an operating strategy.
The Transmission dipstick for a 1999 Honda CRV is located under the hood of the car. It is just below the air intake, and usually has a yellow or red cap.
I have a 99 jetta, and you are unable to check the transmission fluid on your own. You will have to take it to a service station where they will check it for you for free.
pick it up and look at it's little dipstick!!