1998 GMC C3500 TURNSIGNAL HEADLIGHTS AND WIPERS ALL ON AT O

aLL LIGHTS WORK FINE WHEN RUNNING LIGHTS AND HEADLIGHTS ARE TURNED OFF. When running lights or head lights are on the winshield wipers turn on, headlights are dim one high beam and one low beam on, turnsignals lit dimmly. using turnsignals all lights dimmly flash. Just replace multi-switch and nothing changed. Any help ???