Regarding Center Top Vehicle Brake Lights - A Question

[xrunner]

Very informative - thanks!

[VK5RC]

@xrunner  if you can't get to sleep;  re vehicle standards I was interested to see a quite reasonable attempt to Internationally harmonise 'standards',  since 1958 ! https://www.unece.org/wp29.html. - amazingly sensible.  Most of the amendments seem to be in the 1995+ time frame.

[Seekonk]

The real reason is they don't have the space there to mount bulbs.  One year or two years of the Ford Explorer they used a fluorescent lamp. These were nearly impossible to get as there was not enough demand to make aftermarket ones.  The lamp cost about $300 and the power supply was mounted down in the hatch cover.  Figuring out which one was bad was expensive.  Many cut open the light and just put LED in so they could pass inspection.

[Halcyon]

One year or two years of the Ford Explorer they used a fluorescent lamp. These were nearly impossible to get as there was not enough demand to make aftermarket ones.  The lamp cost about $300 and the power supply was mounted down in the hatch cover.  Figuring out which one was bad was expensive.  Many cut open the light and just put LED in so they could pass inspection.

Not to mention Fords are known for electrical issues. In my state, we have yearly inspections for light vehicles over 5 years old, but you still see Ford after Ford with completely non-functioning brake lights, the indicators/reverse lights come on instead of brake lights or they do some kind of strange random dimming of other lights.

Subaru is another car I've noticed that seem to have a high proportion of blown lights. It's usually one of the side brake lights or headlights. I would probably say in any given week 10-20% of Subaru Foresters or Libertys I see on the road have something wrong with their lights.

[xrunner]

The real reason is they don't have the space there to mount bulbs.

They sure do have the room, you must have missed my post where I showed the 2002 Hyundai rear center brake light assembly. I've attached it again here. It plenty large enough to mount bulbs in. It's not only large enough top to bottom and lengthwise, it's also a pretty deep enclosure. Even if it needed to be even larger for some reason, that would not have been a problem to design at all.

Edit: As a matter of fact, the size of the thing (I've taken it apart in the troubleshooting process for the original problem) is seemingly way bigger than it needs to be inside.

[Brumby]

Not to mention Fords are known for electrical issues. In my state, we have yearly inspections for light vehicles over 5 years old, but you still see Ford after Ford with completely non-functioning brake lights, the indicators/reverse lights come on instead of brake lights or they do some kind of strange random dimming of other lights.

Odds on the cause will be a bad earth.

The globes will be fed separate power, but they will have their earth sides connected together in the fitting with a common lead to an earth point on the body.  This earth connection will go bad and the powered globe will find earth through the other globes.  Depending on the circuit topology and exactly where the earthing fault occurs, you get some weird results.

[james_s]

I've seen that in a lot of different cars due to bad grounds. I actually don't recall ever seeing it in a Ford but I haven't really paid a lot of attention. I suspect it's a lot more common in areas where they use salt on the roads. Perhaps Ford grounds the tail lights in an area that is vulnerable to salt corrotion.