Red Indicator Light options

[Hayden40]

First post here, and let me say thank you to all who post! I've learned a ton from you all for the last two years (delivery was a year ago December). You guys are awesome!

I know this has been asked over and over. I have been getting conflicting answers when I talk to FF5 and Blueprint. I'm just about to hold my breath and turn the key for the first time, but I still have an unused red indicator light that is installed on the dash (probably shouldn't have put it there without a plan). It seems like an alternator light would be ideal I suppose. I'm not sure if it is needed with my setup, but need to use the light for something. I'd love to hear specifically how some of you wired it in, or other ideas for it.

Also I've been documenting my build in a non-public you tube channel, specifically for my kids to look back on when their older. More recently made it public, hoping a builder might stumble on it with suggestions. The channel is Hay Roadster! for any of you that enjoy helping new builders out. Thanks in advance, I love the community, and would like to contribute more as I learn.

Here is my setup:
MK4 - complete kit
IRS
Platinum Gauge Set
BluePrint 427 c.i. stage 2 w/ AC+PS
Holley Sniper EFI
Tremec TKO600
wiper kit
battery shutoff


additional add-ons (not sure if any of this helps, but just in case)
hidden marine radio in trunk w/speakers behind seats
ie 427 turn signal
North Racecars AC

[gbranham]

I don't understand using that red light as an alternator light, when there's likely a battery voltage gauge already on the dash. I've never owned a car with an alternator light...why would I need one in this car? I'm sure I'll get flamed for this. Hah! Since you're using Sniper EFI, there might be a trigger wire in there somewhere for oil pressure, or maybe coolant temp, to illuminate the light at a preset value, just as a quick visual indicator of a problem. Some even wire that light to their radiator fan, so they know when it's running, but that seems kind of silly to me. But everyone builds to their needs and desires. There's no wrong or right...just personal preference.

Greg

[Jeff Kleiner]

I don't understand using that red light as an alternator light, when there's likely a battery voltage gauge already on the dash. I've never owned a car with an alternator light...why would I need one in this car?



Let me tell you about why I'm thankful for having an alternator light... When I flung the serpentine belt going 120 on the main straight at Gateway International that red light got my attention immediately and alerted me that I wasn't going to have power steering as I cut down into turn one. Aside from the power steering if I hadn't had the warning I might have run another lap or 2 without the water pump turning---and likely cooked the engine.

Jeff

[Mike.Bray]

Some even wire that light to their radiator fan, so they know when it's running, but that seems kind of silly to me.

If you use the FFR-supplied fan you don't need a light, you can hear it above everything else. Exhaust, wind noise, 747 taking off, my wife when more boxes from Summit show up.....

[Hayden40]

Thanks Jeff, do you recall how you wired it? i have a "1 wire alternator" so i'm guessing one wire from indicator tying to that post and the other to ground? I've seen a few threads with the two indicator wires bridged together with what looks to be a resistor. Not sure I understand what's happening there. The more I research, the more confused I become!

[JJK]

I must have been sent a rarified radiator fan from FFR because I cannot hear it, and this is with touring pipes.

I wired a low fuel indicator light, but it seems to light up on any turn with half a tank or less of gas as the gas sloshes around. Not sure I would go that route again.

[gbranham]

Let me tell you about why I'm thankful for having an alternator light... When I flung the serpentine belt going 120 on the main straight at Gateway International that red light got my attention immediately and alerted me that I wasn't going to have power steering as I cut down into turn one. Aside from the power steering if I hadn't had the warning I might have run another lap or 2 without the water pump turning---and likely cooked the engine.

Jeff

Makes sense for those who track their cars, for sure. I don't think I'll need that insurance for my lazy Sunday drives, knock wood.

[Waterman]

I put my extra red indicator right above the steering wheel as a warning light. Original ideas were for low oil pressure or E-brake but ended up as a brake light indicator. There are times when you just want the tailgater to back off or when you are down shifting or.... A light touch on brake until dash light comes on. Gives some confidence that the rather flimsy brake switch is adjusted and working correctly. Some ideas anyway.
Ant

[BrewCityCobra]

I have a stand-alone red LED on my dash as well. I wired mine as a low-oil pressure idiot light. Easy to wire and completely independent of all other wiring so it is easy to wire in after the fact. Just requires a low pressure oil switch installed on the engine, running a keyed fused power to the LED, and running a wire from the LED to the switch (the switch acts as a ground).

Simple, and useful.

[Norm B]

I used it as a dual purpose brake indicator light. Indicates the park brake is on or I am low on brake fluid. Wired it so that either item provides the ground side of the circuit.

Norm

[TTimmy]

Hayden40,
I’ll check out the YouTube channel later. You’re not allowed to be a voyeur on the forum and not contribute in some fashion, so thanks for making it public!

I acquired a partially started project with a red light already installed to the dash. I intentionally don’t say partially finished a but that’s another story - you can check my build thread for details. Anyway, what to do with that red light? I couldn’t decide. Eventually I ran a wire from the fan circuit so know if the engine is calling for cooling. Is it necessary, no. But these cars aren’t necessary either.


I like Jeff K’s alternator failure indicator. Makes a ton of sense. Might redo things when my dash is back off (still under construction).


As Mike mentioned above, Audible fan that FFR provides indicates the fan is running. I’m thinking of pulling the fan and doing some wind tunnel testing on my coupe… a project for another day.


Welcome to the forum and hope you’re enjoying your build!

[F500guy]

208804

I used 1 of these with an idiot light. Just be aware you if you hook it up directly to the gauge feed in the dash that feeds your volt meter, the voltmeter will read about 1.5 volts lower than actual voltage, but with normal working alternator, that should still be about 12 volts on the gauge and the light will not be lit.

From Ron Francis

[Railroad]

You might consider a shift light. I have some cars that red line very fast, especially in the lower gears. I have the shift lights set below engine red line rpm, I am old and slow sometimes.
good luck,

[Jeff Kleiner]

Thing is that if you’re using a Ford alternator (2G, 3G, etc.) the alternator will not charge unless it has the load of a light or 510 ohm resistor in the exciter wire. I figured that if I had to one or the other it might as well be dual purpose and serve as a lack of charge warning in addition to making the alternator function.

Jeff

[OB6]

208804

I used 1 of these with an idiot light. Just be aware you if you hook it up directly to the gauge feed in the dash that feeds your volt meter, the voltmeter will read about 1.5 volts lower than actual voltage, but with normal working alternator, that should still be about 12 volts on the gauge and the light will not be lit.

From Ron Francis

I used a similar unit from American Autowire, specifically intended for 1-wire alternator applications. It will trigger the light when voltage drops below 11V. I'm not sure about the impact on the volt meter -- I'll have to look at that.

https://americanautowire.com/products/11-volt-alternator-warning-light-module-510287

[Avalanche325]

My red light is a combination low oil pressure / high oil temp. There is no time to look at the dash during autocross.

[JMD]

I know this is an older thread, but if you're using the Sniper EFI and want a high temp warning light (like I did), you can wire it up to the Fan #2 output and set the temp at which it gets activated in the sniper tuning software. This seems to me to be the easiest way to get a high temp warning as that's one thing I definitely want to know about and may overlook in the moment if there are no other symptoms. I like the idea of low oil pressure light too, but think that high coolant temp is more likely to happen in the average car.