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'92 Cutlass Supreme 'Vert - Display Flickering


Gearhedd

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Way back when I had my '90 Turbo GP, I thought I remember reading about a fix for the flickering of the fluorescent display on the factory radio and the DIC. My '92 Cutlass vert has a stock radio & the automatic (digital) climate controls, and recently the fluorescent displays both began this same flickering whenever the parking/headlights are on. The brighter you set the dimmer switch, the higher the frequency of the flickering, and it finally quits flickering & stays on solid when you set the dimmer up to max. All of hte regular illumination bulbs behave fine(no flickering). Is this problem in the dimmer control itself, or is there another control module that I need to check?

 

Thanks In Advance !

 

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I am not overly good with electronics, but could the resistor or solder around the resister be toast? I am guessing full brightness by-passes it and that is what causes flicker.

Light bulbs are much slower to respond to varying voltages. Much slower than vacuum fluorescent tube displays or whatever because they require a very constant voltage to stay running and a higher one for starting.

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Sounds kind of like you might've blown a diode in the alternator, or something like that. Especially if its occurring in more than one module (ie: in both the HVAC module, and the radio, and/or DIS) as you claim it is.

 

Do you have a scope that you could put on the +12VDC bus and see if there's excessive ripple there?

 

 

 

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No, unfortunately, no scope access. However, alternator voltage reads good on vom. I'm guessing it would read lower than norm with fluctuating output? Electronically challenged here, so I haven't a clue. From my faulty memory, I was thinking it was more along the lines of a bad headlight/dimmer switch, as the frequency of the flickering of both displays varies directly with a change in the brightness setting of the dimmer switch.

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UNPLUG THE RADIO, and see if the HVAC illuminations still works.... see if your hvac still flickers or what.....

 

could be a bad alternator (if would need to be removed and tested)

 

it is unlikely to be a headlight switch....

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Turn the stuff on with the key on but motor off, then try the dimmer. If it works fine then remove serpentine belt and start motor and try again. If it works fine again its the alternator.

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Turn the stuff on with the key on but motor off, then try the dimmer. If it works fine then remove serpentine belt and start motor and try again. If it works fine again its the alternator.

 

DO!!!!

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