2000 Mercury Cougar electrical problem with the dash board lights & headlights flicker when l turn them on, l had the electrical system checked and was told that the Alternator was bad had that replaced, however it did not fix the problem can anyone please help.
Thanks

if the light switch is the type you pull-out the problem could be the switch itself or the connector behind it could be lose causing a poor connection

this was a technical service bulletin issued by ford.
TSB00-25-06

Article No. 00-25-6
• CHARGING SYSTEM—HEADLAMPS, INSTRUMENT CLUSTER, RADIO OR INTERIOR LIGHTS FLICKER WHEN COLD—VEHICLES EQUIPPED WITH 2.5L ENGINE ONLY
• ELECTRICAL—HEADLAMPS, INSTRUMENT CLUSTER, RADIO OR INTERIOR LIGHTS FLICKER WHEN COLD—VEHICLES EQUIPPED WITH 2.5L ENGINE ONLY

MERCURY: 1999-2000 COUGAR

ISSUE
Some vehicles equipped with a V6 engine may exhibit a flickering condition of the headlamp, instrument cluster, radio, & interior ights during engine start-up & may continue during the first several minutes of engine idle. After several minutes, the flickering will subside but may not completely diminish. This may be caused by excessive electrical resistance in the battery voltage sensing circuit. Vehicle operation is not affected by this condition.

ACTION

Reroute the battery sense line from the engine cable, untape & remove. compartment power distribution box to the B+ terminal on the alternator. Refer to the following Service Procedure for details.

http://teamwetworks.com/claymore/cougar/tsb00-25-06.pdf

follow the link it has pictures & step by step instructions