Have a 1998(S) 306 DTS and have a big problem with the cooling fans. When the ignition is switched on within secs the cooling fans start running. If you turn the ignition off within 3-4 secs they stop. I have tried replacing the 3 sensors (Blue/Green/Brown) to no avail. Have also checked the relays again to no avail. My next thought (after research) is maybe replacing the BITRON cooling fan control unit, but before I went down this route wondered if anybody else has experienced anything like this?