Turn Headlights On and Dash Lights Go Dim

[short_dustin]

I just drove my '87 T-type and when I turn the parking lights or headlights on, the digital dash lights go all the way dim. I turned the dimmer switch all the way up and the interior lights came on but the dash lights don't change.

Anyone know what the problem could be?

 

[fitz3820]

Do your volts drop when you turn the lights on?? Might have a weal alternator or a bad ground somewhere.

 

[GNVenom]

Defective dimmer switch.

 

[HotAir6 v.2.0]

Did you get this resolved. It's really annoying if you want to drive with your lights on during the day. I have the same issue for a while now and it's time to get it fixed.

It's obviously getting power at the switch or the interior lights wouldn't turn on when it's turned all the way up. I pulled the dimmer switch and cleaned the rheostat and it seems to work fine. Well it varies the resistance when I roll the switch from high to low, whether or not there's another issue with it I couldn't tell.

I still don't have any control over the dash lights so I've started looking at some wiring diagrams to see if I can track the problem down. If all I need is a new dimmer switch then I think that's the easiest fix that tool the longest to fix I've ever had. Where do I get a dimmer switch?

 

[Heskahoka]

If Caspers (GNVenom) says its a dimmer switch, than it probably is.

Highway Stars carries them:
http://www.nos4gn.com/servlet/the-57/Buick-Grand-National-parts/Detail

 

[HotAir6 v.2.0]

Factory service manual says it's either the fuse the dimmer or the ground. Mine turned out to be a bad fuse.