Right stop/turn signal problem

Need HELP PLEASE,,
 The right tail light and turn signal work fine until I press the brake at which time the right tail and turn signal light doesn't work, it goes out until I take off and get off the brake petal.  Anyone have an idea as to the problem..
HELP is really appreciated..  

you have a bad ground connection

either from the tail light bulb to the socket..

or from the socket to the reflector housing..

or from the reflector housing to the car body...


there could also be an issue up at the front of the car where the ground connections from the negative battery to the engine block and from the engine block to the body are...

what year is it???  

please... start with this test.. you will want to  print it out and follow it..



this is how later model cars are all grounded..




do you have a pair of jumper cables that are separated wires... clip one to the battery negative.. the other to extend that one to the back of the car...  now... have somebody operate the turn, tail and brake lights while you touch the tail light reflector housings with the end of the jumper cable thats hooked to the negative battery..    you can also use test 3 or 4 to from the tail light housing to the body...  with the volt meter set to 20 volts DC..   no more than 0.02 volts is to be expected.. from either housing to the body... or to your extended jumper cables from the negative post..

let us know what happens..

this is where mustangs are grounded...

 

It is a 1966 Mustang Convert.

Appreciate your help......

Ron  

This might be a defective turn signal switch in the steering column.  If you have a steering wheel puller, it isn't a hard fix.  Be sure to attach a string to the wires when you pull them up from below, as you will need the string to pull the new wires in the column.  
Bill

1966 coupe
1995 Cobra R

judhorse:
Need HELP PLEASE,,
 The right tail light and turn signal work fine until I press the brake at which time the right tail and turn signal light doesn't work, it goes out until I take off and get off the brake petal.  Anyone have an idea as to the problem..
HELP is really appreciated..

Wayne has it nailed. It's in the taillight housing/bulb socket/ body connection.  After you do all of Wayne's grounding tests and fix any findings, you will still need to fix the right bulb connection however. If it' sin the socket to reflector interface, sometimes a tap on the socket to reflector connection with a hammer will reground it.