Chevy Nova Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
Looking for advice on my 64 Nova headlightlight switch .While rotating the switch to Brighten or Dim The dashboard lights , the dashboard lights will flicker and the switch makes a sound simalar to a loose guitar string . Parking lights ,headlights And instrument lights all are working, but the iinstruments bulbs Will Flicker almost as if contacts are bad in the dimmer side of switch?

Any recommendations on where to purchase a new switch for my 64 Nova ( should I get new old stock or aftermarket OK ) ?
 

·
Moderator
Joined
·
6,517 Posts
On the headlight switches I have seen is for the dash light portion, there is a wiper arm that rotates across windings of wire on a circular insulator.

When the one end of the wrappings of wire has power going to it and then the wiper arm contacts against it, the length of wire is short which means very low resistance so that if you have 12V going into the windings and the wiper arm contact the first inch or so of wire, you would get 12V out.

Since the design is to dim the lights, this wire wrapping of wire is fairly long and now if the wiper arm contacts a section of wire that is now let's say 20" long, then the resistance is more and now with 12V still going in, the resistance of the wire and where the contact arm is making contact reduces the voltage down to let's say 6V and now the bulbs are dimmer. The length of wire in the wrap has resistance.

The contact arm normally is wider than the width of the wrappings to where it makes contact on maybe two or three windings and this is to make sure each degree the contact arm is rotated across the windings, there is always contact between the two.

Normally the wrappings of wire and the contact arm are electrically solid and pass power from one to the other but due to corrosion, sometimes mechanically there is contact but electrically there is not and sometimes by rotating the contact arm across the windings a few times, the friction cleans things up electrically and removes corrosion and then there are no dead spots when going from full brightness to fully dimmed. Sometimes too the tension on the wiper arm is less due to age.

The wrappings of wire on this insulator are tight to help hold them into position but sometimes due to heating and cooling they become slightly loose and now when the wiper arm is wiped across them, a winding or two may ring like a guitar string. I've not seen this with dimmer switches but have heard this ringing in transformers and chokes.

I've been asked a few times at shows since I'm decent with electronics with people asking why their dash lights do not dim or there are spots that they blink off and I normally reply that there is an issue with the switch and every once in a while people say that they have already replaced the switch with the same issue and when they have been replaced they have been using aftermarket ones. I cannot say what ones they have bought or from where but it seems like I see more issues with aftermarket ones than factory ones. Not that one may be better than the other but I would probably shoot and get an original one VS an aftermarket BUT now that I've said that I might buy an original and have issues while one I got aftermarket would work fine. Sometimes it's a crap shoot but the factory one to me would be a better bet.

If you want to try and revive your old one barring a big issue is to buy a contact cleaner to clean off corrosion on the connections and work the switch fully one way and then the other a bunch of times and then if you revive it, every so often during the year, rotate the switch fully both ways a few times to clean things up again.

I get spoiled at work as we have a product called De-Oxit that I use on switches:

http://store.caig.com/s.nl/sc.2/category.188/.f

Jim
 

·
Registered
Joined
·
30 Posts
Discussion Starter #3
Thanks Jim for a extremely informative/ educational reply. I will try as you recommend and exercise the switch and or use contact cleaner. If no luck I will check on EBay fo a 64 NOS switch if not will resort to getting a aftermarket switch. I Will post my end result.

Thank You Again-
 
1 - 3 of 3 Posts
Top