The dash wiring harness is slightly different for the different
switches. The difference is mainly in the lighting for the dash, the
lighting that has the dimmer wheel as part  of the headlight switch.
85-89 had a separate fuse for the dimming lights, late 89 and newer uses
the license plate light fuse for the dash dimming light fuse also.

Using the newer switch in earlier models would keep the dimming dash
lights from working at all.
Using the older switch in newer model would seem to work fine but would
remove all fuse protection from the dimming dash light circuit. Fire or
wiring damage could some day result. 80-84 models had no fuse for this
anyway but 85 on does.

The ignition switch is just the electrical part. The ignition lock
cylinder is just metal that turns with the key. The cylinder part has a
small tab that sticks into a slot in the electrical switch and turns the
switch when the key is turned.

Mark

Aaron wrote:

> Hello all. I'm trying to show my dad that working on vanagon stuff
> isn't that bad. I do have a question about the headlight switch for a
> 91 carat. I was looking at the busdepot site and noticed that 2
> headlight switches were listed. One appeared to be for 89-92 (92?) vans
> and ran about $71 vs. the other that was around $25. Does anyone know
> if the more expensive switch is needed? His headlights require holding
> on the high beam stalk in order to work at all.
>
> One other question...the van has cutout once while driving...almost
> like it was turned off. I think it may have been the ignition switch.
> Looking at the busdepot site again, I see an ignition lock cylinder and
> an ignition switch. What needs to be replaced if an ignition switch is
> going bad?
>
> Thanks!
> Aaron
>