A wiring challenge for Tim or Mike, ..or others if you understand this kind of stuff. Options

[ThePaintedMan]

I've been on a mission to add a second set of brighter, more visible idiot lights since this car is mainly a track car. I bought a set of 2 cheapo 24-led green/red boat lights from Ebay (seen here). I wired the green in line with the existing oil pressure light and it works perfect - very bright and obvious on startup until it shuts off with adequate pressure.

However, I'm still stumped as to how the alternator idiot light is wired and if the same thing can be done with the red one. Someone posted an excellent thread awhile back explaining how alt light is wired to come when the circuit is no longer charging. But I can't figure out how to wire this red light up to work with it in the same way that my oil pressure light works. Obviously when I wire the led light in parallel with the existing alt light, it doesn't work the same way, ostensibly to the added resistance? Wondering if it's even possible to add a second light.

Sorry if this is confusing. I'll take some pics tonight to try and illustrate my point, but as always, thanks for your help in the meantime.

[worn]

But I can't figure out how to wire this red light up to work with it in the same way that my oil pressure light works. Obviously when I wire the led light in parallel with the existing alt light, it doesn't work the same way, ostensibly to the added resistance? Wondering if it's even possible to add a second light.

As I remember it, the problem you face is that the light in the dash uses current running in both directions, depending on the situation. So you would need two LEDs polarized in opposite directions.

Turn the key on and the light filament provides current from the battery to the windings allowing the alternator to bootstrap itself up as the car starts. Then the output of the alternator roughly matches battery voltage and the light goes out. You need this for alternator function! A 1.8-2 watt bulb is needed or the equivalent conductance.

If the main diodes fail, then the alternator will stop producing output. If the secondary diodes are still OK the lamp will see a higher voltage at those diodes than it does at the battery and current flows in the opposite direction, from alternator to battery.

In my TR6, the blinker indicator light on the dash uses the actual blinker lamps opposite the ones signaled as a ground. The current from the indicator is not enough to light up the tail lights, so it works. It saved them a couple feet of wire, but no LED is gonna work easily there!