I did the below procedure years ago and it has now stopped working. Any clue? The TT chip still kicks the fan on at 160 but the manual switch dont work. This came from gnttyp.org. Thanks
High Speed Fan On
The switch will ground the High Speed Fan Relay regardless of engine temperature. To install, run a wire from a ground location to one end of the switch and run another wire from the other end of the switch to the Green wire with a Yellow stripe going from the High Speed relay to the temperature switch connector (which is vertically mounted on the intake manifold just to the right of the thermostat inlet.) You can splice into the wire at any point. The fan will continue to run as long as the switch is in the On position, however, if you leave the switch On when you shut the car off, the fan will continue to run in the high speed mode for approximately ten minutes.
High Speed Fan On
The switch will ground the High Speed Fan Relay regardless of engine temperature. To install, run a wire from a ground location to one end of the switch and run another wire from the other end of the switch to the Green wire with a Yellow stripe going from the High Speed relay to the temperature switch connector (which is vertically mounted on the intake manifold just to the right of the thermostat inlet.) You can splice into the wire at any point. The fan will continue to run as long as the switch is in the On position, however, if you leave the switch On when you shut the car off, the fan will continue to run in the high speed mode for approximately ten minutes.
