I think it is switched to the on-position all the time.
When the interval is switched on, you here a *tick everytime the wipers go.
So I reckon you mean by can't switch off, that they are always on the lowest continious speed?
"Thanks to the reader who suggested that there is a diode in the wiper motor to stop current from flowing back out of the yellow wire (to the washer switch and hence to the washer pump) while the motor is parking. I may not have thought of it for ages, if at all! The diode appears to be sealed within the casing."
I have a similar thing on my 96 CSE. The wipers won't shut off after being used on intermittent on normal speeds - but only sometimes! I have replaced the relay but it still happens. I assumed it must now be either the actual switch or the park mechanism on the motor. Any more ideas?
had this b4 on other cars.. it's usually the park mechanism in the wiper motor.. on the ones I've seen it's like a peg in a slot... the peg was sticking through dirt and grease.. cleaned it up and hey presto..