G'day,

Recently I was messing with the gauges on my late (75ish) van. I noticed that there are a couple of fused plastic nubs next to the speedo bulb holders. This indicated to me that there should be a green tint to the back lights. But there isn't.

The gauges on mine are the only ones I've seen at night. Can someone confirm / deny greenness for me?

I tidn't seem like a particularly technical question, so I fielded it here.
If you are wondering why I was messing with the cluster, it was to patch in a second tach to help narrow down a problem.

my 71 ute has white lights but there was some old green tint that had melted and blocked the light some so i removed all tint and upgraded the lights with lcd globes only the diel lights not warning lights they cause more problems but that is another story

Replacing the alternator light probably would have been bad, right? IIRC it was you that told me that in the first place.

Were they special LED globes or just LEDs you put into such a small space?

I was thinking of just putting LEDs in the holders and putting a small patch lead between the headlight switch and the backlight wire with the right value resistor for the LEDs.

So they were green some time in the last millenia? That must have looked interesting.

the trouble with led's is that they dont pull enough volts so you need to put some darn thing in line and i can't bloody think of what its called
the upshot is the electrical system in a bus needs to have a complete circet or the genny wont charge so even if you blow a globe in the idiot light no charge
keep all that in mind and all will good

Well, if I were determined to replace the alternator light, that one would be a bit tricky.

First instinct tells me to measure the resistance of the bulb and substitute a resistor of the same value so things don't go wonky, but there si something else to consider. The resistence changes when the bulb is lit due to heat, so I'd have to measure that one somehow maybe?

Then there's also the LED drive resistor. Because LEDs are just diodes which can output light, they will gladly let through as much current as is given to them, causing them to burn out, because the more current, the brighter.

So to use them, two things have to be known. Input voltage, and the current they draw. There is a formula that is used to calculate the correct resistance for an LED, but I can't remember it. I'm pretty sure it's all over the place online, and I think even Dicky Smith has it in his catalog up the back.

In the case of the gauge backlights, only one resistor is needed where the positive feed is. This is because they are wired in parallel, and don't draw much current so even a 1/4W resistor is ample for their tiny draw.

I'm just saying this for everyone's benefit and info, Greedy, for anyone that wondered.