Just a couple more notes... SSEiguy and I struggled with this one earlier:

http://www.bonnevilleclub.com/forum/...384&highlight=

It only affects the electronic climate controls because the manual climate controls don't have a VF display.

If you look at the troubleshooting areas:

1. The grey wire provides the rheostat signal (0-12V, dim to bright)
2. The green wire provides the headlamps on signal (0 or 12V, depending on headlamps on or off)
3. The purple and white wire provides a unique VF display dimmer signal (12V to 10V, as the rheostat is rotated from dim to bright)

Notice that a 12V signal applied to the purple'white wire will make the VF display turn completely off! I've tried it. The climate control is expecting the pulse-width modulated signal.

However, in 94, they changed the radio display from VF to a back-lit LCD display, but it appears that the climate control didn't change. Or did it? Is the climate control dimmer now self-contained, or is it simply wired differently?

I am working on getting the 94 wiring diagram, and also checking the part numbers on the 93 and 94 climate controls to see if they match.

Those controls are broken down into 3 part numbers from 92-99.

These are shared:

92/93
94/95
96-99

I now have the 93 and 94 electrical service manuals. The infamous purple and white wire in pin No. 2 disappears in the 94 model! In its place is a yellow wire in pin No. 10. Pins 4 and 5 switch places.

I am going to try to wire in the "headlamps on" signal to my climate control at pin 10. If I don't get a VF display response, I will replace my climate control with a 94 model.

I'll keep you posted (if anyone cares! )

From the user'* perspective: The '93 has red/orange backlighting everywhere, but all the vacuum fluorescent displays (compass, DIC, HVAC, stereo) are blue-green. Later models, maybe starting with the '94 change you mentioned, have red/orange displays which match the backlighting.

I _love_ the dashboard display in the '93, because the contrasting color of the VF displays really makes them stand out. I _always_ get oohs and aahs from people who get into the car for the first time at night. (Almost everyone immediately says that it looks like an airplane cockpit.) I have yet to find a car with a nighttime dash display that'* cooler than this one.

Funny you should mention that...I get they SAME responses...you have to admit...as fas as cockpit lighting is concerned...the 93 SSEi is SUPERIOR...IMO

Yeah, in 94 the radio became all red. Then in 2000 the Bonneville lost the remaining VF displays on the compass, DIC, and climate control.

I like the VF displays.

I'll have to agree here. The combination of displays and colors that the 93 has is superior.

I tried wiring the "headlamps on" signal to pin 10 of the existing climate control to no avail. At that point I ordered a 1994 control head.

I installed it today, and Voila! The dimming capability is back. I wired the existing climate control harness to accept a 1994 control head, which has its own VF dimming capability, yet would still work with the existing HVAC programmer. In addition to the pin 10 wire, pins 4 and 5 had to be reversed.

Here is some part info that I dug up while doing the research:

HVAC control heads:

92, 93 - 16160288
94 - 16201124
95-99 - 16220102

HVAC programmers:

92 - 16183308 or 16183312
93 - 16190465
94 - 16197178
95-99 - 16218972

I'll have to post a techinfo procedure for the complete installation of a newer stereo into the 92-93 models. I will take some pictures soon.

This should close this thread out, finally.

Way to go. Glad you stuck with that one. What was the total $$ damage for this go-around?

Lets see.

Stereo from 2001 Trans Am - $165
New Climate Control Head - $125
Misc. Wiring Harnesses - $5
1994 Serice Manual / Wiring Diagram - $20
Old Radio in trunk (not used anymore) - $10

I don't even want to add it up, because I could have found a 92-93 CD player for around $225.