A/C and radio displays probs

[cinzy0]

Hi@everyone
Pontiac Bonneville SSEi 92
Problem: everything works fine(dashboard, headlights and etc), except for Climate Control and radio displays only. Sometimes it works perfectly, sometimes displays dead(no light up). All radio buttons and A/C buttons light up. A/C always works even without a display
Fuses look ok
What else could it be?
Sorry for my english)

[Roadrunner]

For that year, the climate control display is driven by the radio head unit.
Since the green LED displays can not be dimmed like incandescent bulbs, a variable frequency driver is needed. The driver in the HU uses the voltage signal from the dash dimmer on headlight switch.
I think if you lose dimmer signal, displays will go full bright.
Since you are losing both displays (assuming at same time), I’m guessing the problem is within in the HU (could be a loose connection or bad solder joint).
When it’s acting up, you may want to try adjusting dash dimmer to see if it changes behavior.

[cinzy0]

thx, i will try to look up

And if I disconnect and connect back the battery, displays work for a while(till next car start up or a bit longer)

[cinzy0]

This was due to security system....
Fixed

[Roadrunner]

That's strange.
Pretty sure the 92 HU was not tied to VATS.
Glad to hear you got it fixed though.

[cinzy0]

One of the previous owners put Centurion secrurity system, which so bad and cheap, and it was badly installed
I removed it and now everything works fine

But i have another problem: when i use brakes or reverse-SES light appears

[cinzy0]

Well, the problem is back
Sometimes radio work's fine, most of the time it does not respond with black display. Temporarily helps to remove the cable from the battery, but it wil be the same after some time

A/C sometimes goes dark with radio, but i can use it even without a display (change temp and etc.). Sometimes, after radio dying, display still on, but with full brightness (i can't change it with dimmer)

If radio died, it kills the battery until cable removal

Better to change radio to another?