We've talked about this before. It appears that the 92-93 Bonnevilles have a problem when you install a different stereo, because the stereo on those years controls the VF display dimmer on the climate control.

I have taken the 93 tape deck out, and have installed a newer Pontiac CD player, but I lost the VF display dimmer on the climate control. So I wired an old radio into the trunk, so that I could retain the dimming capability of the climate control.

It seems ridculous to have that old radio in the trunk, and now I am starting to have some problems with the wiring.

What I really need is an electrical diagram for the 1994 Bonneville climate contol so that I can see how it gets the VF dimmer signal. They eliminated the old style radio that year. Does anyone have the diagram, or a good solution?

Fuddy, I ran a jensen head unit, with no problems! What the hell is going on here?

I have not looked up the wiring diagram but I find it hard to believe that the radio itself is controlling the climate display brightness.

Generally speaking, what'* going on is that the headlight switch rheostat is controlling the voltage to the regular dash backlighting circuit (the gray wires) to vary the brightness of the bulbs in the dash. The fluorescent displays of the compass, factory stereo and automatic climate control are actually powered off a different circuit, but monitor the voltage in the backlighting circuit as well.

When voltage is detected in the gray wires, the fluorescent displays dim themselves to try and match it. (To see this effect, try turning the headlight **** rheostat rapidly brighter or dimmer. The fluorescent displays will adjust themselves, too, but it takes them a little time to react to the change, and they lag behind a little bit.)

When no voltage is detected in the backlighting circuit, they stay at full brightness. I'm wondering whether you (the original poster) managed to somehow cut the backlighting input to the climate control when you removed the factory stereo. A wiring diagram would be really useful here.

I have the wiring diagram for the 1993. Diagram 117 in the dealer manual shows both the dark green and grey wires going to the radio. The dark green one enters the radio as the "VF DIM INPUT." It provides 12V+ when the headlamps are on. The diagram says "SOLID STATE." From the radio circuitry exits a purple and white wire, which goes to the climate control. It says "VF DIM INPUT."

The purple and white wire provides a pulse width modulated signal. As the on time (duty cycle) increases, the VF display of the climate control head gets dimmer.

I had the purple wire wired to an old radio in the trunk. The newer radios (94-99) don't have VF displays, nor the VF display circuitry. The key would be to see where the climate control gets its pulse width modulated signal, or how the VF display dims in the 94 model. That'* the electrical diagram that I need.

Will: I'm not sure why it didn't have an effect on yours, because others have had this same problem.

Anyone confused yet?

So you haven't figured where th pulse generator is yet?

Or the flux capacitor?

Seriously, mine worked fine. I wonder if someone before me found a workaround. It dimmed fine with the jensen.....

Thanks for the reference; I'll go and look it up tonight...

Right, Vacuum Fluorescent Dimmer Input. I'm still mildly surprised that the climate control display is relying on a completely-different, completely-unrelated component for its display driver. After all, the thing is otherwise a completely self-contained little box. I know; I've removed it once or twice over the years.

Mine'* still nice and bright, fortunately.

You might also find a troubleshooting chart; e.g. "CLIMATE CONTROL FAILS TO DIM WHEN LIGHTS ARE ON" or something like that.

Me, for starters.

what is this, the 93 SSEi convention?

:?: hmmmmmmmmmmm mine must be different..cuz my climate control in non-electronic....so don`t matter on cd deck...my dimmer worked when i put the 99deck in ..maybe just a electronic climate control thingy

Oh, are you still here?

I'm tempted to pull my stereo and check my display. Maybe I'm just getting old with Turtle.