[chairmankaga]

Here’s a weird one. My speedo, tach, and clock have no illumination. The headlight/high beam and turn signal indicators in the tach work, just not the green illumination for the actual gauges. My auxiliary gauges are fine and the potentiometer that controls brightness works fine. All the fuses are good, wiring is intact and checked out. Is there a junction or ground wire for just that circuit that might worked loose? Any other ideas? Makes driving after dusk more entertaining than it needs to be. Ha.


Sent from my iPhone using Tapatalk

 

[tomhenneka]

The illumination for those 3 gages is daisy chained from the center gage cluster illumination. Power for the center cluster comes from the fuse box; power for the 3 gages comes from the center cluster.

 

[chairmankaga]

And it seems in series, with the clock first in that series. So if, just for example, you’d unplugged the harness from your clock while working behind the dash and figured why plug it back in since it doesn’t actually work but the motor makes an obnoxious clicking sound, then your other gauges won’t illuminate. Or maybe it’s just my car.
To paraphrase Clarkson, every Alfa is unique because no other Alfa has the same set of problems as yours.


Sent from my iPhone using Tapatalk

 

[mechtild]

Try the illumination dimmer switch. Maybe it's just turned off

 

[Alex73]

My auxiliary gauges are fine and the potentiometer that controls brightness works fine

Try the illumination dimmer switch. Maybe it's just turned off

All gauges are dimmed with the potentiometer. The cable for the illumination and dimming the speedo, RPM and clock gauges is so far as i remember a black/white on the second place from the left on a multiconnector. It is the left white multiconnector behind the auxilary gauges (european ´82 GTV6).

Simply try it with a test lamp if there is voltage on the cable out of the multi connector (and the dimmer is on). The cables are crimped in an angle connector - maybe the black/white cable is broken.

 

[johntennyson]

Mine (an '84) does that sometimes. Most of the time, actually. It seems to be the headlight switch on my car since cycling the switch ("turning it off and on again" --IT folks thought they invented that, eh?) or flipping it between high and low beams usually makes them come on.

For me, at least!

 

[vintagemilano]

Did you resolve this? If not, you haven’t mentioned changing bulbs. I did have one car with symptoms like that and it ended up being every single bulb. It actually had led’s in it, they were all bad. I’m thinking they didn’t like to run on dimmed voltage. I don’t know, put plain bulbs in and it’s been good.

 

[SamSteinig]

Mine (an '84) does that sometimes. Most of the time, actually. It seems to be the headlight switch on my car since cycling the switch ("turning it off and on again" --IT folks thought they invented that, eh?) or flipping it between high and low beams usually makes them come on.

For me, at least!

Hey John, this seems to be EXACTLY the issue (and symptoms) with my '79 Alfetta GT. See my thread here:

Problem with instrument lights/running lights when...

On my '79 Alfetta GT I have a problem with the instrument lights/outside running lights NOT going on when the headlights are turned on. The headlights and hi-beams work fine, but I can't really drive at night without the outside running lights or dash lights not working. At first they worked...

www.alfabb.com

Did you ever dig into your switch assembly to try to fix it?

 

[chairmankaga]

Did you resolve this? If not, you haven’t mentioned changing bulbs. I did have one car with symptoms like that and it ended up being every single bulb. It actually had led’s in it, they were all bad. I’m thinking they didn’t like to run on dimmed voltage. I don’t know, put plain bulbs in and it’s been good.

Yeah, I have a post further up with the resolution. The clock harness was loose. That's all it was. The lighting is in series from the clock, so there was no passthrough to the other gauges. I've never seen such dependency on electrics in series as I have in this car. Talk about cascade failure potential!