See the following site:
We have a 1998 Bounder Motorhome (with ford engine) how do we replace the headlight switch?
You replace the bulb the same as a 1998, which is answered further down the page.
the headlight assembly needs to come out in order to change the bulb ive had to do that to my 98 as well.
There are two clips on the wall that holds the headlights. Push the clips away and pull the headlight housing out.
the bumper will have to be removed.
the headlight assembly needs to come out in order to replace the bulb.
changing the bulb
If you can't get to the back of the light assy you have to remove it from the vehicle and the bulb screws in.
How to replace 1998 Toyota corolla headlights
There is no 1998 CTS
drop the bumper and take the headlight housing out