Is it possible to add timed interval wiping to a Zafira B if it doesn't already have it? It's an option, and mine (second hand, 1.9 SRi) doesn't seem to have it.
If so, is it mechanical or a software mod?
The manual says to push the stalk down, wait until the desired interval is reached, then move the stalk back to the timed interval wipe position (- -). There's no change in the interval when I push the stalk down.
I fitted the Omega relay and stalk to my Cav 3 a few years ago and was very happy with it.