Dashboard lights dimmer
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From: Boulder Creek, CA
Mine was iffy, then I sprayed some de-oxit up there, and it works much much better.
Could also..not knowing a better way...pull the plug on it, and test for 12v to it as well.
Could also..not knowing a better way...pull the plug on it, and test for 12v to it as well.
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Joined: Jul 2010
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From: San Diego, CA
I can't speak to later cars, but here are the details for my early car. I just "refreshed" my non-op dimmer this week on my 1981 S Euro, as I had no dash or clock lights at any dimmer position. If the clock light works but not the dash, it is unlikely to be a dimmer problem since both the dash lights and clock light feed off the output of the dimmer.
There are two plastic pins on the back of the dimmer unit fitting into the underside of the dash and the whole thing is tightened down with a Phillips-head screw. You can wiggle the dimmer out after loosening the screw -- I'm guessing it would be a pain to rethread if you take the screw all the way out since it's pretty far up there. Two spade-type electric plugs (One is 12v in from the light switch, the other has 2-leads going to the dash lights and the clock light) on the side of the dimmer.
There was lots of oxidation on the underside of the sweep contact at at the "full-on" contact preventing current flow. The resistive wire coil part looked fine. I slid some fine grit paper between the wire and the sweep contact (grit towards contact) and ran the wheel back-and-forth 5 or 6 times to sand off the oxidation, then wire-brushed the flat full-on contact at the end of the wire coil. After cleanup, I checked the resistance with my meter (0 ohms at full on, about 18 ohms at dimmest setting), sprayed a little Dexoit (great stuff!) on the wire coil and on the contacts, popped it back in, and, thankfully, all dash/clock lights restored. Time=15 minutes.
There are two plastic pins on the back of the dimmer unit fitting into the underside of the dash and the whole thing is tightened down with a Phillips-head screw. You can wiggle the dimmer out after loosening the screw -- I'm guessing it would be a pain to rethread if you take the screw all the way out since it's pretty far up there. Two spade-type electric plugs (One is 12v in from the light switch, the other has 2-leads going to the dash lights and the clock light) on the side of the dimmer.
There was lots of oxidation on the underside of the sweep contact at at the "full-on" contact preventing current flow. The resistive wire coil part looked fine. I slid some fine grit paper between the wire and the sweep contact (grit towards contact) and ran the wheel back-and-forth 5 or 6 times to sand off the oxidation, then wire-brushed the flat full-on contact at the end of the wire coil. After cleanup, I checked the resistance with my meter (0 ohms at full on, about 18 ohms at dimmest setting), sprayed a little Dexoit (great stuff!) on the wire coil and on the contacts, popped it back in, and, thankfully, all dash/clock lights restored. Time=15 minutes.
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From: Shawnee, KS, USA
On my '90, the dimmer rheostat looks like this:
On closer examination, you'll see that there is a lower wiper that contacts the resistor coil and there's also an upper wiper.
And, FWIW, on the '90 (and I'm guessing many other model years), any break in the wires to this rheostat (or if the rheostat is internally not making contact) will prevent the instrument lighting from illuminating all all when the main headlight switch is in any position other than off.
I used pure DeoxIT (not the spray kind, the D100L kind; I'm guessing both would work, but I just happen to use the 100% kind) on both of those contact surfaces and mine works nice and reliably now.
On closer examination, you'll see that there is a lower wiper that contacts the resistor coil and there's also an upper wiper.
And, FWIW, on the '90 (and I'm guessing many other model years), any break in the wires to this rheostat (or if the rheostat is internally not making contact) will prevent the instrument lighting from illuminating all all when the main headlight switch is in any position other than off.
I used pure DeoxIT (not the spray kind, the D100L kind; I'm guessing both would work, but I just happen to use the 100% kind) on both of those contact surfaces and mine works nice and reliably now.
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From: Shawnee, KS, USA
