Originally Posted by SSEiguy
Hey fuddyduddy121 -
I had totally forgotten about this topic being here... Glad you kicked it back up to the top.
Turns out the splicing of the wires did not fix the HVAC display issue for me either... so I've been working on the issue on and off for the last couple months. Here'* what I've found so far:
This "issue" only affects 92 and 93 Bonnevilles with the digital
HVAC display/controls. The HVAC VF dimmer only works properly when fed through the radio first. Direct wiring won't work... the display goes black. Not hooking up the wire at all causes the display to be at full brightness (which is the way mine is right now).
I thought about stashing the original 92 stereo in the trunk, too, but thought of another approach that I'm going to try. We know that you can install a later model stereo into the 92-93 models successfully, as you and I have both done so, but the problem lies with the HVAC display. I got to thinking... the 94 Bonnie has the newer style stereo, but has the same (or at least similar) HVAC display as the 92-93s, so they must have changed the VF dim circuit wiring in 94. The 95+ cars had a major makeover with the HVAC system, so I know those aren't even close to ours.
So I hit the library and started digging through wiring diagrams, and sure enough! The HVAC display from a 94 -should- work in a 92-93, provided you swap the wires at pins 4 and 5 (Data Link Circuit) and wire in the VF dim circuit directly instead of having it feed through the stereo first. All the other pins on the 94 match the 92-93 units.
I am going to pick up a 94 HVAC display as soon as I can find a cheap one to test my theory. Will let you know how it goes, and if it works, will provide the wiring changes necessary to do it.
BTW - What kind of mods did you make to your 2001 stereo to get it to fit into the dash opening? Mine lines up good on the right side, but the holes and alignment pin don't line up on the left.
I was beginning to think I was crazy with this problem, until I saw others had it here. It seems as if everyone with an aftermarket stereo is a 92 or 93 SSE/SSEi must have this problem.
I should take some pictures of the install. The R side lined up perfectly, but as I recall, I had to drill a hole in the radio bracket on the L side for the peg, and also had to drill a hole in the dash on the L side to hold the lower piece for the screw.
In addition, I had to take the rear bracket off the old radio, saw off the part above the midpoint, and then screw it on to the new radio, because it didn't have the rear bracket. Don't forget about the slightly modified wiring harnesses.
By the way - The Trans Am radio is just like the 94-99 Bonneville Radio. It is not like the new ones in the 2000-2002 Bonnevilles. This means that it will work fine with our situation. (It might have been from a 2000 Trans Am, not a 2001; I can't remember for sure)
In addition, I dug up the correct pin connection for the steering wheel controls. It turns out that pin No. 13 on the top row (third from right) is the correct pin to receive the signal. As I recall, there was one other pin that also works with the steering controls, but it'* almost like it was desinged for controls on a different Pontiac, because it makes all of the buttons do the wrong things (might have been pin 14). On the existing 92-93 radios, the SWC goes to the separate connector on the other side of the radio, but on the newer ones it goes right to the 20-pin connector with the other wires.
Let me know how the climate control thing works. They only made that 94-climate control for one year; I think you can tell the difference from the "AUTO" button; it'* different looking than the 88-93 model.