Where is the distibutor cap on a 1993 Jetta Wagon?

Here is a picture for you:

if there is no spark at any plug i would check you coil, then distibutor cap and then distributor then theres a little module on the distribtor that can go that i would check as a last resort cuz there expensive. hope that i helped

You didn't specify which size engine you had, so I have included both engine firing orders of your model year...

sounds like the rotor arm or distributor cap check carefully for cracks

First item you need to go after is the slow turning. have the battery charged and load tested. Once that the battery is verified as fully charged and good, put a volt meter between the two posts and crank the engine. voltage should not drop below 9.5V If it does, It is likely that your starter is worn out. If your distributor has a bolt that goes through an ear that is part of the distributor, you cannot adjust the timing. It is pre-set and controlled by the computer. Make sure you have the firing order correct and that you are indexing from the correct position on the cap.(turn the engine to tdc on the timing scale and rotor should either be pointing directly 180 degrees away from #1 or directly at it. Make sure you are getting spark and fuel when engine is cranking and it should start.

the firing order is 1-3-4-2..if you remove dizzy cap and look around top of of distributer you will see a small line etched in to the alluminium.when the rotor arm points at this you are on no 1 so no 1 on the dizzy cap will also line up with this.follow round in clockwise direction for 3-4-2. cheers

Firing order is 1  3  4  2  and start at one, (the top) go one at a time, and move in a clockwise rotation.  looks like this:
                                                                   1 
                                                            2              3                                                                        4

The module is INSIDE of the distibutor.

Disconnect the Battery, remove the distributor cap, then the rotor, then the leak cover.

The ignition coil has a little spring at the top and is held in by two large screw-bolts.

The ignition control module has 3 wires attached to the top and one on the side. It is held in with two screw-bolts and should come right out.

It all sounds like you have a bad computor. If you are not getting fire from the coil. The source will lead you back to the brain source, (The Computor). Go to the local junk yard to get another one at half price.

Sounds like the distributor cap is cracked and allowing moisture in. I would start there.