EEs Wanted: Wiring Diagram Help Needed

lelandEOD

SILVER Star
Joined
Aug 21, 2012
Messages
1,018
Location
Northern Nevada
So, here's the deal. I want to add a small panel to my dash that will house warning lights that are not already incorporated into my Dakota Digital HDX gauge cluster. The DD cluster has a CEL, diesel Wait to Start, etc., etc.

The 1HZ engine that's going in has a couple extra senders to monitor the fuel sedimenter, air filter, oil level, and alternator charge status.

I've sourced a bunch of 3mm LEDs and have talked to a really awesome laser engraver in town who will make the panel. It will look something like this:

NEW WARNING PANEL.jpg


The plan is to mount in on the dash near the headlight switch. Somewhere near here:

IMG_5593.JPG


But, before I commit to punching a rather large hole in my dash, I really need to have a warm and fuzzy that I both understand the wiring diagram and that I can replicate the needed circuits. I'm getting a little fuzzy in my wiring diagram-fu with the diodes and resistor seen in the charge light bulb circuit.
The air filter, fuel filter, and brake fluid/vacuum circuits all appear to be pretty simple ground switches - no problem there. I also think I can work out the bulb-check relay (I know it isn't necessary or anything, but it would be kind of cool if the brake warning lights came on in the ST1 position).

But, the charge light circuit is getting the better of me. I don't understand what the diodes (and resistor) do and I'm struggling to understand how the charge light even works. The bulb shouldn't illuminate when the ignition switch is in the IGN position and the alternator is charging, right? Can anyone help me understand how this circuit is supposed to work?

If anyone can look at this and help me understand how it works, I would greatly appreciate it.

Here's the charging circuit:
Screen Shot 2018-11-03 at 4.00.28 PM.png


And here's an excerpt of the gauge cluster diagram that shows several of the warning light circuits:

View attachment 1823851

Screen Shot 2018-11-03 at 4.03.13 PM.png
 

rusty_tlc

Dain Bramaged Member
 
Joined
Jun 23, 2005
Messages
13,470
Location
Reno, NV
I have no idea how much or little you know about resistors and diodes so don't be offended if I dumb it down to much. Think of diodes as check valves, they only allow current flow in one direction: the way the arrow points. Resistors are like valves that limit the current flow and prevent the diode from burning up.
The physics of electricity are actually a bit different but this model works for explaining how diodes and resistors work together.

BTW Toyota schematics give me fits and I've beenworking in Electronics for a long time.
 

lelandEOD

SILVER Star
Joined
Aug 21, 2012
Messages
1,018
Location
Northern Nevada
I have no idea how much or little you know about resistors and diodes so don't be offended if I dumb it down to much. Think of diodes as check valves, they only allow current flow in one direction: the way the arrow points. Resistors are like valves that limit the current flow and prevent the diode from burning up.
The physics of electricity are actually a bit different but this model works for explaining how diodes and resistors work together.

BTW Toyota schematics give me fits and I've been working in Electronics for a long time.
Thanks, Dan. What you posted is literally the extent of my diode and resistor knowledge. I get the anode-cathode basics; I was just really struggling to understand the circuit. However, the Rosetta Stone of Alternator Basics was just unearthed and now I think I found the missing link. I did not know that the regulator grounds the warning lamp through the "L" output until I found these diagrams:

Screen Shot 2018-11-04 at 8.15.50 AM.png
Screen Shot 2018-11-04 at 8.17.10 AM.png


Ding ding ding!

Now I'm pretty sure I can figure out the charge circuit. Now, whether I can figure out how to make a little breadboard circuit for the warning lamps is something else all together!
 
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