Most Fords have the connectors for heated screen at the base of the screen, so you'll have to pull off the wipers and scuttle panel and should be a 4 pin plug on the Street Ka. Screen resistance should be less than 5 ohms on each side.

You could try putting a pair of resistors in the plug to mimic the element.

I'm still in doubt whether this is relevant to airbag module if I'm honest!