Instrument Panel Bulbs

[golf73]

The bulbs that are in contact with the circuit board in the instrument panel aren't coming on. Warning lights all come on (oil, charging, high beams, turn signals) just the gauge illumination lights to the left side of the speedometer and the fuel/temp gauges not coming on.  Any ideas?

Edited July 27, 2017 by golf73

[Mike Self]

First thing to check:  look at other lights that can be dimmed (like the 4 way flasher lamp inside its switch) and the radio illumination.  If they're not functioning either, the problem is in your headlight switch.  The dimmer control on those switches are a known failure point--especially since the newest ones are now 41 years old.  You might try turning the dimmer knob back and forth several times to see if you get any lighting; if not, the switch is gonna have to come out for cleaning, continuity testing and possibly replacement.  If the non-instrument illumination bulbs are functioning properly when you turn the dimmer knob, then...

 

You either have a break in the circuit board or a problem with the multi-prong plug that connects the instrument cluster with the car's wiring harness.  

 

cheers

mike

[PaulTWinterton]

45 minutes ago, mike said:

if not, the switch is gonna have to come out for cleaning, continuity testing and possibly replacement.

 

Would cleaning also change the brightness of the bulbs at full-on.  The intensity seems quite dim, unless it's completely night.  I've often wondered if it's a function of age or intended.

[Mike Self]

3 hours ago, PaulTWinterton said:

Would cleaning also change the brightness of the bulbs at full-on.  The intensity seems quite dim, unless it's completely night.  I've often wondered if it's a function of age or intended.

It can.  The dimmer function on the headlight switch is a very simple resistor; a coil of resistance wire that a contact travels over; the further you turn the knob to brighten the lights, the less resistance wire is included in the circuit.  This whole contraption is pretty much out in the open, and can both get dirty and corrosion on the contacts, thus creating more resistance.  And the movable contact can lose tension over the years, so it no longer makes a firm contact with the resistance coil.  

 

Try turning the knob back and forth several times with the lights on; if you notice the bulbs either flickering or getting a bit brighter, your dimmer switch could do with some cleaning.  Good old spray tuner cleaner (for those of us old enough to remember TVs with rotary channel changing switches) will clean the contacts.  

 

One more thought--the bulbs in your instrument cluster are probably the original ones, and they do get dimmer over the years, so you might treat the cluster to new bulbs.  LEDs will be nice and bright, but most for that application are not dimmable.  

 

mike

[deanres]

Mike LED's bought on Amazon installed dimmable and much brighter. No idea how long they will last, but right now they are working fine after about 9 months. 

[Dudeland]

Just as a FYI if you go with Superbright LED's  in your dash you have to trim the wire in the base connector so it is only on one side, otherwise you just end up blowing the fuses. I wasn't smart enough to figure this out myself, I got it from another member.  I can't remember who. 

 

[golf73]

On 7/27/2017 at 8:11 AM, mike said:

First thing to check:  look at other lights that can be dimmed (like the 4 way flasher lamp inside its switch) and the radio illumination.  If they're not functioning either, the problem is in your headlight switch.  The dimmer control on those switches are a known failure point--especially since the newest ones are now 41 years old.  You might try turning the dimmer knob back and forth several times to see if you get any lighting; if not, the switch is gonna have to come out for cleaning, continuity testing and possibly replacement.  If the non-instrument illumination bulbs are functioning properly when you turn the dimmer knob, then...

 

You either have a break in the circuit board or a problem with the multi-prong plug that connects the instrument cluster with the car's wiring harness.  

 

cheers

mike

Hi Mike,

 

The "4-way flasher lamp inside its switch" - are you referring to the hazard switch? If so, yes the lamp is functional, as is my aftermarket stereo cassette player lighting. When I rotate the headlight switch left and right it dims/brightens the lamps that are currently working. All of the bulbs are new Osram bulbs, so it's not the bulbs.

 

I don't get why all 4 gauge bulbs don't work when all 4 telltale lamps do work - they're all on the circuit board. The hazard switch may be suspect, as I have pulled it out and repaired it, because of the "wouldn't turn off" issue. It now blinks when I use my right turn signals, but not when I use the left!

 

Thanks for your help Mike

 

-Ryan

Edited July 28, 2017 by golf73

[John_in_VA]

4 hours ago, deanres said:

Mike LED's bought on Amazon installed dimmable and much brighter. No idea how long they will last, but right now they are working fine after about 9 months. 

 

What are/where does one find "Mike LEDs?"

[Simeon]

49 minutes ago, John_in_VA said:

 

What are/where does one find "Mike LEDs?"

 At Mike's place. 

 

Just kidding 

[Mike Self]

12 hours ago, John_in_VA said:

LED's bought on Amazon installed dimmable and much brighter. No idea how long they will last, but right now they are working fine after about 9 months. 

Yeah, I'd like to know the source of dimmable LED instrument cluster bulbs.  I've looked on Amazon and all the ones I saw were specifically noted as "non-dimmable."  My instrument illumination is pretty dim, and I know it's not the headlight switch so it's probably those original 44 year old bulbs.  

 

mike

[deanres]

LUYED 10 x T10 3W 6 SMD 5630 5730 Super Bright White 194 168 2825 W5W LED Car Lights Bulb

LUYED

Sold by: Hot Light Team

[John_in_VA]

6 hours ago, deanres said:

LUYED 10 x T10 3W 6 SMD 5630 5730 Super Bright White 194 168 2825 W5W LED Car Lights Bulb

LUYED

Sold by: Hot Light Team

 

Thanks for the follow-up!