Idiot lights

SuperDave

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This may seem like a dumb question, but has ANYONE wired up (or known of) an alternator idiot light for a 73 C-body before?

I'm ripping out the dash assembly and installing a complete aftermarket gauge set to go along with my Musclecar Makeover. 6 gauge setup with a 200 MPH GPS speedo (w/turn signals & hi beam indicator), 8k tach, volts, oil, temp & fuel (73-10 amp of course), PLUS a matching clock for a total of 7 gauges. I've already yanked the extra plug in the water pump housing to mount the temp gauge sending unit, allowing me to keep the Hot/Cold idiot light sending unit, and the aftermarket sending unit for the oil gauge is a dual lead unit with 1 for the gauge & the other for a light (comes on at 11psi or less). The factory ammeter leads behind the dash are shorted together and taped off with a heavy cable going from the hot lead on the 130 amp alternator (because I'm running electric fans, fuel pump, MSD Ignition & an 800 watt sound system) wired direct to the battery to prevent the bulkhead connector from overheating. The only issue I'm running into is how to wire an idiot light for the alternator. I want a His & Hers dash, gauges for me and lights for her. I've been looking online, but for this style of alternator (2 field wires & external voltage regulator) Ma Mopar only wired up the dashes with an ammeter gauge, no idiot light.

Any ideas? Pics would be a big plus and earn you my deepest respect. Thanks in advance
shopping.jpeg
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bigmoparjeff

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The charge indicator lamp in cars that are so equipped is controlled by electronics inside the voltage regulator.

If you hadn't already invested in a high output alternator, a fairly simple solution would be to install a GM alternator on the car that has an internal voltage regulator and charge lamp circuit.

Your best option would be to build this simple circuit to control a warning light. It's adjustable, so you can choose the voltage at which it goes on.

https://www.electroschematics.com/12v-lead-acid-battery-low-voltage-indicator/

12V-Lead-Acid-Battery-Low-Voltage-Indicator.jpg


Jeff
 

John Kirby

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Idiot lights have their purpose. My son's Durango has the dash buzz loudly and the display says "CHECK GAUGES!!" in bright red text. If there is an issue. Had the oil pickup clog up and this saved the engine. Gauges are useless if you are not looking at them. It's also why cars now have a low fuel light. When was the last time you saw a car on the side of the road out of gas?
 

fury fan

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Older thread but something worthwhile to add.

Some, if not all, of the M-bodies had a warning light built into the ammeter. But IIRC somebody might've said even though marked as an ammeter, it was in fact a voltmeter? I dunno. An FSM might have more info.

I have that gauge @Big_John showed above. It's a nice economical piece and adds a modern touch but with several caveats.

1. There is NO built-in circuitry for triggering the warning light condition - you must add that externally.
2. As you can see in the pic above, lighting bleeds out into neighboring indicator areas and isn't evenly bright. It would look much better if it had crisp compartmentalization between the indicator functions.
3. It seems about .020" larger diameter than a standard 'metal can' 2-1/16" gauge. It has a threaded barrel for installation, which might be a marine, or some new standard? I'm seeing lots of gauges on Amazon using this installation method. A secondary issue to that is the bezel is NOT much bigger than the threaded body, so if your hole isn't accurate it'll fall right thru.


@SuperDave
I found this on ebay awhile back and it's a bit more versatile for mounting location. It includes all the circuitry, and has options for various voltage ranges.
I think this is probably your best bet for what you described for your gauge layout. Unfortunately it doesn't have any labeling for what it's purpose is, but perhaps putting it close to the voltmeter is sufficient.

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SuperDave

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@fury fan , I "built" the circuit given by bigmoparjeff, and I now have a low voltage idiot light. I've got it set to come on at 4 volts (any lower and nothing works - period!) and it starts doing at 12.4 volts, going off completely at 13 volts.

The original factory low fuel light circuit didn't work for me though, it doesn't like LEDs, something to do with the current draw of an incandescent bulb needed to heat up a resistor or a bimetallic circuit. But then I found an adjustable low fuel level module circuit that doesn't care if you're lighting an LED, an Edison Radiation bulb or a florescent bulb. It ties I to the same input as the gauge. So it's all good. I will have my His-&-Hers dash with gauges and lights.
 

jimmyessbee

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Idiot lights have their purpose. My son's Durango has the dash buzz loudly and the display says "CHECK GAUGES!!" in bright red text. If there is an issue. Had the oil pickup clog up and this saved the engine. Gauges are useless if you are not looking at them. It's also why cars now have a low fuel light. When was the last time you saw a car on the side of the road out of gas?
Well... You used to know because you saw them walking down the road with a gas can. Now they just dial 911.
 
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