If you do a search you'll find another thread on this, one comment was the ign. switch. But that was on an SL, I think the system is different. Mine does the same thing so I bought a flasher for it but I have yet to install it because it is broken down in CT, fan clutch blew apart and took out Rad, but thats another story.

I paid 65 bucks for it so it seems to be a cheap fix, retail was 292.