AU2: Check Illumination Control Circuit

With the ignition key in the OFF position, disconnect the radio connector and/or compact disc player connector. Turn the headlamp switch to the parking lamp position or the headlamp position. Operate the light switch rheostat resistor from the dimmest position to the brightest position. Measure the voltage on the Pink/Black wire at the radio connector and/or compact disc player connector while operating the light switch rheostat resistor. See WIRING DIAGRAMS  . Does the voltage vary from approximately 9 volts (dimmest position) to approximately 0.2 volt (brightest position)? If yes, service the radio and/or compact disc player at an authorized Ford Audio Service Center. If no, service the Pink/Black wire between the radio and the timer module.