Pontiac Repair: Pontiac transport signal light R Rear, pontiac transport, ground signal

Question
Hello I am a retired mechanic and need and answer to a signal light problem.  All works fine except when the light switch is turned on or at night when the headlights go on automatically.  The right rear signal light flashes along with the reverse light and when the brake pedal is applied the signal light arrows in the dash are dim light. However when the brake is applied the dash arrow is bright on the left and right side when a signal is used.  When the lights can be turned off everything seems fine.  Any hints would be greatly appreciated.  Thanks  Joe

Answer
Hey Joe:

sounds like you have a bad ckt board for that side of the van. there lighst are in a ckt board in the rear. chances are that the connector is bad that goes into the board as well. The connector melts and then you loose the ground signal to the lamp and the truck is searching for a ground when the park or turn or stop lamps are appliec and the ground is comming as a back feed though the other filiments in the bulbs. pretty common issue. good luck :-)