Dash lights flicker

[Fbks_Cruiser]

Recently the dash lights began to flicker. I can’t notice any flickering in the headlights, taillights or dome light. Does it while running and not running with key on or off.

I put LEDs in the instrument cluster about a year ago. No problems until recently. I checked the instrument cluster ground and the wiring harness connection at the back of instrument cluster. All of the bulbs flicker at the same time so I think it is somehow power supply to the cluster. Or could it be the printed circuit?


Maybe the dimmer mechanism in the headlight switch? I did turn the knob back and forth several times to kind of rub a new contact area on the rheostat. Made no difference.

Ideas?

[HO455]

Please correct me if I am wrong. The LEDs have their own power supply. They are not running 12 vdc straight from the light switch. If so I would test the 12+ power to the power supply with an Analog multimeter. Using an analog meter makes it easier to see momentary fluctuations in the power. With one eye on the meter and one on the LEDs try to observe if the meter fluctuates when the LEDs flicker. If no fluctation I would suspect the power supply. Conduct the same test on the output of the power supply to confirm this.
If it does fluctuate then move to the light switch. Testing both sides of the dimmer resistor to confirm.
If all this looks good then you have a problem with the ground side. Look first to the ground for the power supply. Run a separate ground wire to the power supply (if it has one) and see if the problem disappears.

[Fbks_Cruiser]

I’ll need to get an analog multimeter. I only have a digital one. The bulb in the heater control is also dimmable with the instrument cluster lights so that tells me it is tied to the same circuitry. It is still an incandescent. I don’t notice flicker there. Don’t know if that is because it is not LED or if that indicates the problem is at the cluster.

I’ve studied the wiring diagram but can’t quite decipher how the dimming mechanism in the light switch works. It looks like the instrument cluster lights draw power via a 20gy wire from the fuse panel. The other side of that is a 16dg wire from the switch. So the 16 dg wire gets variable voltage from the switch?

Also the instrument lights flicker regardless of whether the switch is turned full bright or “dimmed”. These LEDs are not dimmable. Maybe they are flickering because they are getting too low voltage? But they didn’t flicker when new.

[HO455]

A digital meter can work but it isn't as easy to see this kind of problem. Many digital meters have circuitry that mask minor fluctuations, making it hard with some meters to detect fluctuations.
Here is a link to the dash light circuitry. The ceramic part of the light switch closest to the dash is the actual resistor that does the dimming. (First photo. Second photo harvested from VetteVet's post in the thread. Once again kudos to him and his vast knowledge.)
LEDs have a minimum voltage they operate at. Drop below that and they shut off. My guess is that your operating on the edge of the minimum voltage. Both sides of the wiring to the LEDs can be the source of the problem.


http://67-72chevytrucks.com/vboard/s...d.php?t=593546

[Fbks_Cruiser]

Thanks, I thought VV would likely have addressed this problem before. Guess I just didn’t use the right search terms. I’ll grab an analog multimeter and do some testing. Or just go back to incandecents!

[kensousa]

I have the exact same issue with my '71.
LED swap worked great for a few months and now they flicker all the time.
I'm contemplating going back to regular bulbs as well.

[HIGHWAY BY THE SEA]

Mine did exactly the same thing when I put green LEDs in my 67 GMC dash lights. Now they do not work at all. I don't know what to do.

[Fbks_Cruiser]

I’ve been meaning to get back to you guys on this but got delayed by my daily driver 4runner losing oil pressure. Grrrrr. Was driving the ol reliable 72 gmc every day!

Any way I pulled one of the LEDs from the instrument cluster and put in an incandescent. The other LEDs still flicker but the incandescent doesn’t. I also tried an old school analog (needle gage) voltmeter and it held rock steady. So.... I blame it on the cheap Amazon LEDs. So I bought some others from SuperBright LEDs hopefully better quality. Haven’t tried them yet. I’ll let you know how they work out. It make take a while to know for sure as the cheap ones lasted almost a year.

[Fbks_Cruiser]

So I just swapped out the Cheap amazon LEDs for these l got from superbrightleds.com.

https://www.superbrightleds.com/more...t-car/206/919/

I went with white, but are also available in green, blue, red and other colors.

No more flicker! I cant say how long they will last since I probably won’t be needing to drive with lights on until next fall. I’ll keep you all posted.

But beware: if you just google superbrightleds, another vendor pops up as your first choice with a logo that is very similarly named superlightingled.com with the same font and colors. Their 194 LEDs are the same cheap ones I got from Amazon. Make sure you go to superbrightleds.com.