Gearhedd Posted December 5, 2009 Report Share Posted December 5, 2009 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 ! Quote Link to comment Share on other sites More sharing options...
oscar_wilde Posted December 5, 2009 Report Share Posted December 5, 2009 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. Quote Link to comment Share on other sites More sharing options...
rockfangd Posted December 5, 2009 Report Share Posted December 5, 2009 possibly a bad headlight switch? Quote Link to comment Share on other sites More sharing options...
pitzel Posted December 7, 2009 Report Share Posted December 7, 2009 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? Quote Link to comment Share on other sites More sharing options...
Gearhedd Posted December 7, 2009 Author Report Share Posted December 7, 2009 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. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted December 8, 2009 Report Share Posted December 8, 2009 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.... Quote Link to comment Share on other sites More sharing options...
Hairdo12 Posted December 8, 2009 Report Share Posted December 8, 2009 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. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted December 11, 2009 Report Share Posted December 11, 2009 Could just need resoldering. That fixes a good deal of old GM electronics. Quote Link to comment Share on other sites More sharing options...
Pabz Posted December 11, 2009 Report Share Posted December 11, 2009 My vote is the headlight/dimmer switch, replace with a JY one. get a few for testing. Quote Link to comment Share on other sites More sharing options...
Crazy K Posted December 12, 2009 Report Share Posted December 12, 2009 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!!!! Quote Link to comment Share on other sites More sharing options...
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