1997 Mark VIII neon bar and CHMSL wiring problem

mustpaike

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Hi everybody. I am in need of your help with a wiring issue regarding the neon bar on the trunk lid and the CHMSL under the the rear window. Now before you start, I have already checked the search function and read just about every topic related to others having issues with either neon or the CHMSL, on and off the forum. However this has not helped me much.

To start from the beginning. My factory neon ballast went out, blowing the brake and tail light fuses. I replaced the fuses and for good measure, disconnected the neon bar altogether. And all was good (albeit without the neon). However recently I ordered a new ballast from the guy who builds and sells them on eBay in the US and had it wired in by professionals according to the instructions included.

This however has caused two problems:
First the less serious problem - when parking or headlights are switched on, the neon bar is lit up, but only with single stage function, as a parking/running light. Nothing happens to the brightness when I press the brake pedal.
The second problem is very serious - whenever the tail lights are turned on, the CHMSL is also faintly illuminated. When brake pedal is pressed, the CHMSL becomes brighter along with the rest of the tail lights.
This behavior makes both other drivers as well as the police think that the brake lights are completely shorted out and inoperable, so obviously driving it as is is not an option.

A technician in my local shop (which is focused on working on American cars, I am not located in US) explained, that a parking light signal sent to the neon bar is also somehow making it to the CHMSL, causing it to glow. When the neon bar is disconnected, no issues and the CHMSL is once more only activated by pressing the brake pedal. I looked at the CHMSL photos on eBay, and there are just 2 bulbs and 2 wires on the harness for the CHMSL, so nothing complicated there.

Now, from the older posts that the search function dug up, I learned that the CHMSL should be wired straight to the BOO only, while everything else goes through the lighting module in the glove compartment. If this is really the case, then this kind of activity should be impossible? Right?

Does anybody have the wiring diagram for the neon bar as well as the CHMSL? Or ideas how the two could be wired together? Or where to start looking for the fault? Could this be an issue with the part of the wiring that moves with the trunk lid? Or some kludge? Honestly I cannot fathom any good reason why these two lights would even be wired this way.

Even if the CHMSL lighting up as a parking/running light is factory-intended, I want to delete that feature ASAP while also be running neon again, even if single stage only. Getting the neon bar working again as a two-stage running/brake light would be a small added bonus.
 
Agree, " Did you contact the ballast maker?" I am by far no expert on electrical but sounds like a ground problem on the neon to me.
 
Hi everybody. I am in need of your help with a wiring issue regarding the neon bar on the trunk lid and the CHMSL under the the rear window. Now before you start, I have already checked the search function and read just about every topic related to others having issues with either neon or the CHMSL, on and off the forum. However this has not helped me much.

To start from the beginning. My factory neon ballast went out, blowing the brake and tail light fuses. I replaced the fuses and for good measure, disconnected the neon bar altogether. And all was good (albeit without the neon). However recently I ordered a new ballast from the guy who builds and sells them on eBay in the US and had it wired in by professionals according to the instructions included.

This however has caused two problems:
First the less serious problem - when parking or headlights are switched on, the neon bar is lit up, but only with single stage function, as a parking/running light. Nothing happens to the brightness when I press the brake pedal.
The second problem is very serious - whenever the tail lights are turned on, the CHMSL is also faintly illuminated. When brake pedal is pressed, the CHMSL becomes brighter along with the rest of the tail lights.
This behavior makes both other drivers as well as the police think that the brake lights are completely shorted out and inoperable, so obviously driving it as is is not an option.

A technician in my local shop (which is focused on working on American cars, I am not located in US) explained, that a parking light signal sent to the neon bar is also somehow making it to the CHMSL, causing it to glow. When the neon bar is disconnected, no issues and the CHMSL is once more only activated by pressing the brake pedal. I looked at the CHMSL photos on eBay, and there are just 2 bulbs and 2 wires on the harness for the CHMSL, so nothing complicated there.

Now, from the older posts that the search function dug up, I learned that the CHMSL should be wired straight to the BOO only, while everything else goes through the lighting module in the glove compartment. If this is really the case, then this kind of activity should be impossible? Right?

Does anybody have the wiring diagram for the neon bar as well as the CHMSL? Or ideas how the two could be wired together? Or where to start looking for the fault? Could this be an issue with the part of the wiring that moves with the trunk lid? Or some kludge? Honestly I cannot fathom any good reason why these two lights would even be wired this way.

Even if the CHMSL lighting up as a parking/running light is factory-intended, I want to delete that feature ASAP while also be running neon again, even if single stage only. Getting the neon bar working again as a two-stage running/brake light would be a small added bonus.

Agree, " Did you contact the ballast maker?" I am by far no expert on electrical but sounds like a ground problem on the neon to me.
The ballast has an adjustment on it for taillight , and brake light ! Use a small straight slot screwdriver to turn the screw about 4 turns counter clock wise to adjust for taillights ! That can cure you difference between the taillight/brake difference ! I will check my instructions for installing the ballast ! Sonny
 
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