I have been reading through my chassis manual and the forum here for a few days now. My problem is with my gauge & dash lights. I recently rewired my '67 chevelle. After having my headlights short out on me last week, I decided I want to go through and re solder and make some better connections. While diagnosing my headlight issue I was trying to figure out how to tie my illumination for my gauges and dash so that I can control the brightness using the light switch. I currently have all Autometer gauges and the illumination for these are sourced from switched 12v when the light switch is turned on.

I am a little confused on what I have been reading here on the forums. I have seen people post that the dash lights get its power from the tail light circuit (usually a brown wire) that runs from the light switch. This makes perfect sense to me, as a lot of late model cars are still wired this way for safety. However, I have also read that with a stock setup, the gauges are connected to the green wire running from the switch as well. When I look in my chassis manual at the electrical schematic, this green wire goes to the fuse panel, and not anywhere to the cluster. In fact, the schematic doesn't show the gauge illumination in the tail lamp circuit either. Is the continuity between the guages and the tail lamp circuit handled inside the light switch or do I have to actually splice into the tail lamp circuit with my illumination wiring, and if so what's with the green wire and how does it tie into the picture.

I am really just trying to get an idea of how the car was wired originally and go from there.
Of course with the wiring harness I have the wires are different, I have a wire from the fuse block for guages (which I am currently not utilizing), and then of course my power for the light switch. Does the light switch have two 12 volt sources running to it? I know there are plenty people here who too have built some custom dash panels. I would just like to pick your brain to help straighten out this wiring mess and circuitry.

Im sorry for the mumbo-jumbo it is a bit confusing, but to be honest I AM confused! Thanks in advance.

Why don't you just tie the gauge lights into one of the gray dash light wires.

wow! ok, on the headlight switch, is a rheostat the dash lights work off of that and dim or brighten as the switch is rotated. not sure of the color wire, but, look under the dash at the back of the gauge panel the most wires the same color will be the dash light wires.

The issue here is I am not running the stock wires. Like I said, I have run an aftermarket harness in the car. Neither the wiring is stock nor the dash. I built my dash and none of the old lights are there. Hence the reasoning behind me trying to understand the circuitry. If it was as simple as splicing into existing wires I wouldn't have an issue.

Sorry that my original post was so unclear.

So your dash lights work as they should or not?
I mean do the dim down by rotating the headlight switch?

The wiring diagram I have for a 69 doesn't show enough detail, it shows the gray dash light wires coming from the taillight fuse and doesn't even show the inst. lamp fuse at all. :confused:

Trying to understand the circuitry on a home brewed system would be impossible for me too, especially since I can't see it or do any testing.

Yes the factory dash lighting is fed from the tail light circuit. The switch contacts that feed the brown wire also feed the green wire. Before getting to the green wire the power is routed through the dimming resistor.

Be sure to use an inline fuse so that a shorted dash light doesn't take out the tail lights. The factory green wire connects to one side of the "INST LAMPS " fuse, the other side of the fuse has the gray wire that feeds the dash lights.

Yes the factory dash lighting is fed from the tail light circuit. The switch contacts that feed the brown wire also feed the green wire. Before getting to the green wire the power is routed through the dimming resistor.

Be sure to use an inline fuse so that a shorted dash light doesn't take out the tail lights. The factory green wire connects to one side of the "INST LAMPS " fuse, the other side of the fuse has the gray wire that feeds the dash lights.

Thank you! That is exactly the information I was looking for!