Dim lights in dash

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60sMoparGuy

60sMoparGuy

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The lights in the dash of my 68 barracuda are very dim. The reostat on the headlight switch only makes them dimmer. Could the problem be in the connection ( dash to wiring)? Could something be cutting the voltage to these dash lights?
 
probably the headlight switch itself is going bad, seen it before where you either have no dash lights or very dim, turning the switch makes them either worse or they turn off
 
Find "the little" instrument fuse which is at one end of your fuse panel.

The way this works is, the dimmer gets power from the tail /park fuse, so make sure the tail lamps are bright, IE getting good voltage.

Then power goes through the dimmer, TO the inst. fuse, and then off to all the lamps

So check voltage at both ends of the fuse. If you can twist the dimmer far left and get nearly battery voltage, the dimmer is OK.

The dimmer is just a simple exposed rheostat, with a moving contact, so it's subject to damage, wear, and corrosion.
 
inertia said:
You may have a few bulbs burnt out, making it dimmer than normal..
Click to expand...

TrailBeast said:
And the rest of them dusty. :D
Click to expand...

And they do get black. If you are getting good voltage at the fuse, check the harness connector pins on the pc board

check the lamp sockets contact fingers and clean or replace

burnish / clean the board around the socket contacts

and of course "the bulbs"
 
LED's don't play well with varied voltages.
ie, dash light dimmer won't work right.
 
65Val said:
Works great in my F*rd pickup...are Mopes a diff. system?
Click to expand...

No, they are the same as far as how they dim the bulbs.
The experiences I have had with LED's is that they drop off suddenly when the voltage gets below a certain threshold, unlike a filament bulb.

If that is the case then I have been holding off changing for no apparant reason.
 
I don't keep up with the good and bad of LEDs, so many being third world imports, etc. "The thing" about the dimmer is that it's not a voltage divider, it's a simple series rheostat. What this means is that the CURRENT LOAD on the rheostat establishes the output.

To put this another way, if you were to unhook all bulbs from the dimmer, and check it's output with a voltmeter, IT WOULD NEVER CHANGE. It would always remain "same as battery," because there is no load

My take, after reading some posts, is that "some" LED replacements don't put enough load on the dimmer to allow it to control.

And, as TB says, many LEDS have a sort of threshold

The "thing" about LEDs:

LEDs are, as the name implies, a DIODE. They are in operation when conducting, which in simple terms, turns them into a SHORT.

So why don't they destroy something? Because they require either a built in or separate CURRENT LIMITING resistor.

Once you increase the supply voltage so that the LED start -- and remains -- in conduction, and producing light, some of them don't change brilliance very much
 
Hundreds of headlights switches have been replaced due to a failed dimmer function.
Its quite simple to install a jumper over that function component. Result is 100% of current regardless where the knob is turned to. The dome lamp function stays intact as well. if this doesn't make the lamps bright as possible, the fault is definitely in the connections from here to chassis ground.
There are only 4 bulbs for illumination in a rally panel. If 1 is burned out you would have a unlit area.
The other 4 are on indicator circuits. Those do utilize the same chassis ground path so if the problem was in that, those bulbs would also be dim. That is Excluding the park brake lamp. it grounds at the switch on the mechanism. If that 1 bulb burns brighter than any other, all others equally dim with the dimmer feature bypassed, the ground path at the inst' panel is suspect.
Sort of a process of elimination diagnosis, before attempting to remove that inst' panel.
Hope it helps
 
IF you would rather go ahead and throw a new headlight switch at it...
Here's a tip, The new headlight switch will have an extra male space connection that is only used for a chassis ground path where the switch is mounted in plastic ( other models ).
Ignoring the fact that your panel is pot metal and adding a ground wire from that supplied terminal to a good ground location can work like magic for everything about the panel ( except for the park brake lamp of course ).
 
67Dart273 said:
I don't keep up with the good and bad of LEDs, so many being third world imports, etc. "The thing" about the dimmer is that it's not a voltage divider, it's a simple series rheostat. What this means is that the CURRENT LOAD on the rheostat establishes the output.

To put this another way, if you were to unhook all bulbs from the dimmer, and check it's output with a voltmeter, IT WOULD NEVER CHANGE. It would always remain "same as battery," because there is no load

My take, after reading some posts, is that "some" LED replacements don't put enough load on the dimmer to allow it to control.

And, as TB says, many LEDS have a sort of threshold

The "thing" about LEDs:

LEDs are, as the name implies, a DIODE. They are in operation when conducting, which in simple terms, turns them into a SHORT.

So why don't they destroy something? Because they require either a built in or separate CURRENT LIMITING resistor.

Once you increase the supply voltage so that the LED start -- and remains -- in conduction, and producing light, some of them don't change brilliance very much
Click to expand...

Thanks for the interpretation Del. :D
Sometimes I don't explain well enough.

That rheostat explanation was spot on.

One other note,
When using low draw replacement bulbs like LED's that use a quarter the voltage, you can usually get a device to put the amperage load back in so things like flashers still flash(the old style flasher) and they make an electronic flasher that does not rely on a load.
They are a simple electronic on/off switch.

In my case I use LED's to lighten the load draw on certain wiring in my car, so adding an artificial load to compensate for it is just taking away the advantage of using LED's.

Excuse me while I go order some blue LED's for my dash lights.:D
Gotta try them now and see what they do.
 
TrailBeast said:
No, they are the same as far as how they dim the bulbs.
The experiences I have had with LED's is that they drop off suddenly when the voltage gets below a certain threshold, unlike a filament bulb.

If that is the case then I have been holding off changing for no apparant reason.
Click to expand...

Ok, TB, I hear ya...but I hardly ever (read: never) run them that dim...usually on full brightness anyway, so it's really not a problem for me. Having brighter lamps was the reason I changed to them in the first place!
 
25 years ago I removed the complete wiring of the nopar and replaced it with a Ron Francis and have not had a problem since.
 
65Val said:
Ok, TB, I hear ya...but I hardly ever (read: never) run them that dim...usually on full brightness anyway, so it's really not a problem for me. Having brighter lamps was the reason I changed to them in the first place!
Click to expand...

My sentiments exactly.
So I'm going to order some for my dash and hope they work right.
If not no biggie, they can stay on full.

Thanks for the info.
 
Is the 194 bulb the brightest we can use?
The 158 isn't as bright correct?
Thanks Ron
 
LEDs are polarized but our bulb holders are not. Each bulb will need to be bench tested before the panel is installed.
The LED cluster lamps have looped wire contacts like the OEM bulbs but their wire is so small the connection in our OEM sockets is good one minute and gone the next.

Sylvania #2825 is a brighter, long life, incandescent bulb.
They're about 5.50 per pair and available everywhere.
 
Every connection between the light and the switch has the potential for corrosion. I cleaned up the bulkhead connectors and the fuse panel on my 73 Dart to clear up a similar problem.

Tried LED lights. I don't get much dimming effect through headlight switch. It does dim a little.

PS: Don't try red LED on Whiteface gauges. :eek:ops: Makes the gauge needles nearly disappear at night.
 
Blue is no good either just go with white 194 leds and you will be able to see at night.
 
My dash cluster has been on the bench for almost a week now. I've been researching the LED's along with contemplating the ammeter bypass. I'm quite challenged when it comes to electrical, so none of this is scientific.....

I picked up some #194 LED White bulbs today & just hooked them up to bench test them.

Here's a couple pics of the existing factory style #158 bulb & the #194 LED purchased. They're not installed yet, but I'm encouraged as they look quite a bit brighter!

View attachment P1090940.JPG

View attachment P1090942.JPG

View attachment P1090944.JPG
 
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