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Topic: Dimmer switch gone bad? (part 1) (Read 1317 times) previous topic - next topic

Dimmer switch gone bad? (part 1)

Well, this is for information only, since the dimmer switch can't really be fixed, only replaced. But for those who want to know why high/low-beam switch doesn't work any more, or maybe why the lights won't come on at all, or why the steering column feels hot or smells like melting plastic...



Here's a "normal" switch I got from the wreckers, along with some un-melted plugs and a few inches of wire.



Here's the outside, where the signal lever plugs in.



You can just see the guts, with the springs and contactors for the signals and whatnot.






Off to the side is the dimmer switch. The cutout in the metal is probably to let the excess heat out. Or for you to be able to say "Yep, it's melted alright!" Want to open up it up and have a look? Okay.



Four (4) screws, Torx #10 works, though it feels a little loose. Maybe a #12-1/2, if they exist?



The halves will spring apart a bit. Not to worry. Slice the anti-rattle foam at the joint.



Lift off the top, and you have the contact pads, The signals are the ones in the middle. The 4 dots at the top left are for high-low headlights. They're connected diagonally by a  spring-loaded bar. The 2 flat pieces just below them are the flash-to-pass contacts, activated by the springy plunger in the next few pics.



Here we have the signal contactors (triangular), the dimmer flip-flopping thing (lower left) and the flash-to-pass plunger (sticking out from the green thing).
Death awaits you all with nasty, big, pointy teeth.

1988 5.0 Bird, mostly stock, partly not, now gone to T-Bird heaven.
1990 Volvo 740GL. 114 tire-shredding horsies, baby!

Dimmer switch gone bad? (part 1 & 2)

Reply #1 –
Here's the rest, since someone changed the board to only allow 9 linked images per post (my Speedo post had 31!).
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You can see the little springs under the dimmer contact bar.



The bar snaps onto the plastic block with T-shaped ends. Looks beefy, doesn't it? Well, it's a delicate little bugger, and a bit too much heat caused by high-watt bulbs, dirt on the contacts, or just normal use can melt the plastic block into an unrecognizeable blob (sorry, no pics) that jams the bar from moving, and oozes all over the contacts.



Even this seemingly good switch might soon be a victim, as the 3 dimmer terminals are a lot darker than the others. It could be just a different type of metal, or they're actually being affected by the heat of a bad connection. Either way, rewiring the car so the dimmer only has to control some relays (which would power the lights) would remove any possibility of a meltdown.
Death awaits you all with nasty, big, pointy teeth.

1988 5.0 Bird, mostly stock, partly not, now gone to T-Bird heaven.
1990 Volvo 740GL. 114 tire-shredding horsies, baby!
 

Dimmer switch gone bad? (part 1 & 2)

Reply #2 –
Quote from: MasterBlaster
Either way, rewiring the car so the dimmer only has to control some relays (which would power the lights) would remove any possibility of a meltdown.

Already done ;) I also rewired the car so the ignition switch only controls relays...

I'll merge this post with the other one
2015 Mustang GT Premium - 5.0, 6-speed, Guard Green - too much awesome for one car

1988 5.0 Thunderbird :birdsmily: SOLD SEPT 11 2010: TC front clip/hood ♣ Body & paint completed Oct 2007 ♣ 3.55 TC rear end and front brakes ♣ TC interior ♣ CHE rear control arms (adjustable lowers) ♣ 2001 Bullitt springs ♣ Energy suspension poly busings ♣ Kenne Brown subframe connectors ♣ CWE engine mounts ♣ Thundercat sequential turn signals ♣ Explorer overhead console (temp/compass display) ♣ 2.25" off-road dual exhaust ♣ T-5 transmission swap completed Jan 2009 ♣