How to Change the Ignition Switch on a '78 VW Bus. By Brad Clausen

Before you start, this is what you will see:

Empty the air pressure from the washer tank and disconnect the negative battery cable from the battery before starting! 

First, you have to remove the steering wheel which means taking the horn button off to gain access to the hub. Insert a thin screwdriver blade (I use a utility knife blade)
between the horn button and the surrounding metal ring.  Do not pry up on the metal ring! Gently pry the button off and you get this:

Pull the wire from the terminal.  Using a 24 mm socket, remove the nut. 

Lift the steering wheel off.

Remove the four pan head screws on the wiper/turn signal switch plate.  I've removed 3 in the above picture.  From underneath the column cover, pull the three wiring plugs downward from their connectors.  One is for the wipers, one for signals, and the final for the ignition switch.

Gently lift up on the switch arms at the base and remove the switch assembly.  You will need to pull the hoses from the washer switch once it has cleared the housing. 

Now, pull the spring and expanded metal sleeve from the column shaft (the sleeve is still in place in this picture):

Now the tricky part.  There is an access hole in the lower part of the cover.  In this picture, I've already removed the cover for clarity and to show the hole:

Inside this hole is a factory tamper-proof bolt that clamps the switch housing to the column tube.  Since it does not have a head to get a socket on, you have to drill into it with a inch bit about inch deep.  You can then hammer a screwdriver into it and turn to remove.  This is what the thing looks like once removed:

When you replace it, use an Allen head cap screw like this one:

Remove the two 13 mm bolts under the dash that secure the column to the dash and the 10 mm bolt way up under the dash that holds the back of the bracket to the front of the bus:

Let the column drop back from the dash.  Looking up inside the housing from the bottom, locate the aluminum switch housing.  I had to tap gently upward on this with a long drift punch until the assembly was free from the column.

Lift the housing off.  Locate the small screw that holds the ignition switch to the switch housing.

Pull the switch free and install the new one.  Reinstall everything by reversing these instructions.  Be sure to tighten everything to specification.