I love your blog! You are so thorough in explaining your answers to the many varied questions. Now I have one I hope you can help me with.
I have a 66 Continental Convertible that has a weird brake light problem. It seems that the passenger side brake light doesn’t light at the same brake pedal pressure as the brake light for the driver’s side. A somewhat light pressure on the brake pedal that is enough to brake the car to a stop from a slow to moderate speed brings on the driver side brake lights, but the passenger side brake lights only light when a very firm pedal pressure is applied. All the turn signals work properly, as do the tail lights.
Looking at the electrical drawings, it seems like there is only one brake light switch circuit (unless there has been some undocumented modifications,during production or by an owner over the years).
Thanks in advance for any suggestions of things for me to check.
Hi Robert –
Sounds like News of the Weird! Sometimes though it doesn’t take too much to upset a circuit. You are correct, more brake pressure can’t send more voltage to the right brake lights. Two possibilities come to mind though. First make sure that all of the brake lights are on and have the same brightness when they DO work. The bulbs on one side may be incorrect for the car. Second there may be a bad ground at the right side bulb location or a bad connection at any switch or relay that leads to the right brake lights. The circuit for the turn signals, four way flashers and brake lights on the 1966 Lincoln is complicated and can be difficult to diagnose. You could check another possibility by applying the brakes slowly and have a helper tell you when the left side illuminates. At this point stop the pressure on the pedal with the left side on and wiggle the turn signal lever in the center ( neutral ) position area and have your helper observe for the right side to light up. If it does, the turn signal switch could be internally faulty or if you have the “tilt wheel” option it could be out of adjustment. When diagnosing it is important to concentrate mostly on the wiring for the right side and watch for some previous wiring repair that could be defective. All connections and grounds can be suspect. It is very good that you have the wiring diagram indicating the wire colors. I hope that these suggestions help to lead you to a quick repair.