Cadillac CTS Neon CHMSL Need advice on Neon lights

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tinmanSC

tinmanSC

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Help!

I have, in a great many pieces in my garage, my friend's 2004 Cadillac CTS with the 3.6L engine. The Center High Mounted Stop Lamp (CHMSL. this thing: https://www.youtube.com/watch?v=R0GD6JTCPnA) is not working. It is not LED as I thought, but rather 2 neon bulbs. Neither of those bulbs is working. Inside this brake light assembly it has what seems to be a transformer with the words:
PHILIPS
3222 021 01311
Wk 3 25
Customer Reference: 282 267
(I tried to preserve the spacing)

There are 2 neon bulbs just over a foot long and a 2-wire pigtail sticking out the back, which connects to the larger assembly which has the reverse lights and license plate, etc... in it. I've tested and verified that the pigtail going into the transformer is getting 12v DC, as expected, on the white wire. The bulbs seem fine, no cracks or breaks are evident.

How do I go about tracking down the problem? I understand that these neon transformers hike the voltage up into the stratosphere, so I'm hesitant to hook up my little multimeter to it without guidance. Anyone here work with neon lights and have some advice?
 
Originally Posted By: Rand
thats a very good question you need a GM tech or someone familiar with that wack system..

I tried googling for 30s or so and found this

http://www.cargurus.com/Cars/Discussion-t3782_ds445823

I read the same thing, in fact that's that guide I used to disassemble the light. But it doesn't tell me how to diagnose the problem. He replaces the transformer and 1 of his bulbs, but is that the problem in this case? I don't know. I'd rather not throw parts at it and see what works, which I why I asked if anyone here has experience in neon lighting. I have none. =(
 
If its real neon lighting, it needs around 1000v at very low current. For a car where the initial power source is DC, you need a boost convertor- a solid-state oscillator and current drivers that create an AC voltage to feed to a transformer, which then steps it up to high voltage. For neon lighting, the AC can be used directly if the switching speed is high enough to avoid flicker, but they might rectify it to reduce the chance of radio interference and also to guarantee no flicker. High switching speed also lets the transformer be a whole lot smaller than a 60-hz neon sign transformer would be.

The most failure-prone thing will be the oscillator/current driver part of the setup, but its probably all in one non-serviceable lamp driver module if I had to guess.
 
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