New dash GEN1 GEN2 workaround ideas.

[FridgeBrilliance]

Ok, so things have gotten to the point with the new sheet metal dash where all I have to do is figure out what to do with the gen lights. I almost screwed the pooch and committed to converting to 12V just because of this, then the poltergeist that is doghead invaded my dreams and admonished me and mandated that I find a better solution.

So, what I would like to do, since they have to remain indandescent (everything else will go to LED if that is possible, IIRC only the gen 1 and gen 2 light must be) is use something like this:

2905

Problem is, I have no idea what to search for, or if there is even anything like this that will hold the correct bulb. Any ideas?

 

[cliffyp]

I have no idea if I'm right but it would seem like you could snip the wires for the gen lights before they get to the instrument cluster and reroute them to another location for a light instead of them flowing into the board behind the cluster. I guess you would still need to use a bulb that offered the correct resistance but it doesn't seem like there's any other reason the flow would have to go into the board on the back of the instrument cluster. Warthog, I'm I right on this or way off?

 

[FridgeBrilliance]

The board is getting completely eliminated. My main concern is maintaining that resistance so that the 24v circuit works as intended, and I have some sort of mounting solution that will work for those lights while maintaining an overall military issue appearance.

The whole dash is a sheet of aluminum, with all VDO gauges that will use new sending units, all other lights like the turn signals will go to LED. The shop that is doing the actual wiring and sender work assures me that the whole PCB can be eliminated.

What I do not know how/what to look for is appropriate sockets/housings for the bulbs.

 

[FridgeBrilliance]

Just saw another thread, will M1031 PTO indicator light housings/lenses work? Anybody?

 

[MarcusOReallyus]

1. Measure the resistance of the stock bulb.
2. Go to Radio Trash and buy two resistors of the same value as the stock bulb.
3. Install the resistors somewhere behind the dash where you can service them if needed. (HIGHLY unlikely!)
4. Use an LED to indicate correct function of the alternators.

Now you have resistors to keep your alternators happy, and your dash is all nice pretty LEDs.


BONUS: Resistors are going to be FAR more reliable than bulbs.





Done.

 

[Skinny]

I dig this idea but you can't use a bulbs resistance value because it drastically changes when you light it up. Measure amperage through the gen light instead. Then take the voltage and divide it by the amperage. This will give you the correct resistance value you need.

I'm sure if you googled it, I imagine someone has a writeup on Pirate or some hot rod forum. Wait...hot rod builders can't do wiring so they install a one wire alternator

 

[Skinny]

Replacing vehicle alternator warning lamp with LED

Very good reading for something you are looking to do. I am very good with automotive electronics but am by no means an electrical engineer. Looks like these guys have discussed replacing the charge lamp with an LED and using the correct resistor as well.

I am really happy that Al Gore invented the internet. This was the first hit on a google search (can we get an LED emoticon?)

 

[MarcusOReallyus]

I dig this idea but you can't use a bulbs resistance value because it drastically changes when you light it up. Measure amperage through the gen light instead. Then take the voltage and divide it by the amperage. This will give you the correct resistance value you need.

You are right!


Tanks for the correction.

 

[Skinny]

No problem!

As soon as I read that, I immediately could here my high school shop teacher yelling in my ear..."YOU CANT MEASURE BULB RESISTANCE TO CALCULATE AMPERAGE!!!!!!"

He was good at his job, I could only hope that I verbally assault my students enough for that to happen.

 

[M923driver]

Why deal with a bulb or LED at all? How about a volt meter or ammeter for each alt? Just a thought

 

[SouthernSteel]

Now thats a thought.

Why deal with a bulb or LED at all? How about a volt meter or ammeter for each alt? Just a thought

Now a digital meter for each alt is that sounds awesome. VDO offers those i would think you could adapt one for that purpose.They offer the whole cluster with bezel for the 81-87 chevys.Expensive though.But the digital gauges one for each alternator would be a great addition.Though cant wait to see pics no matter what ya do.:]

 

[FridgeBrilliance]

2 Voltmeters would substitute the lights and the circuit would still work as intended? If so I would much rather go this route, though not with digital.

Thanks for the help and search-fu assistance guys. I really need to do some reading up when it comes to electrical systems, I am completely ignorant of how this stuff works.

 

[MarcusOReallyus]

You'd still need the resistor for functionality, but that's easy to do. They can be behind the dash, out of sight. Use the meters for telling you what's happening.

I will probably go this route myself. Using a bulb for resistance isn't the best design I've ever heard of.

 

[M923driver]

If you need "resistance". I have a teenager you can borrow/have/take over payments....

 

[FridgeBrilliance]

Ok well when I think about "resistor", all I can envision is one of the little dinky bits I have to solder on, like you would see on a PCB, are we talking about the same thing? Or something substantial I can actually wire in?

 

[MarcusOReallyus]

You can crimp one it, or solder it. Depends on the size you need. You do need to get them big enough to handle the current. When you've measured the current the bulb takes, multiply that by the voltage, and you'll have the watts that the resistor will need to handle. Radio Trash should have an assortment.

Here's an idea of what's available:

High Power Resistors,Manufacturer of Power Resistors,High Power Resistors Supplier,Power Resistors Manufacturers,India


Here's more info on the concepts:

Resistor Power Rating - Resistor Wattage Rating

Tell ya what: you measure the current those bulbs are drawing and post it here, and one of us will figure out what you need and reply back. I know there are a few, and probably quite a few, of us who are familiar with this stuff and can help you out.

Deal?

 

[FridgeBrilliance]

Again, the awesomeness of SS shines. Met my second member in person today and got some solid help later. Can't beat it folks.

 

[Dukeboy]

Subscribed, I'm in a simular situation. looking forward to your solution.

 

[Warthog]

Why not use GM's repair guide to find the answer?

What the shops use to check the units is a 10 ohm resistor rated at 6 watts.

Read page 8 and look at the diagram.

It would be nice to have an indicator light.

As usual YMMV.


View attachment Alternator 27SI.pdf