bulb out indicator

Or 3 if you want to sense pairs. Or - with one quad-comparator, 2 pairs and 2 singles.

I couldn't do pairs though...cuz if it senses one goes out before the other then it will let me know that a light is out..is rather have 6 leds...the 2 tail light always on and the 2 trail light always on/brake/turn...so that would be 2 single and 2 dual filament

"Pairs" meaning a pair of tails, a pair of brakes etc - not a pair of filaments in a single bulb. It's too difficult discriminating a 7A or 23W outage from a &W + 23W combination. Pairs may still be fine - especially when pairs of bulbs on one side (ie, dual-bulb tail or stop lights). Knowing otherwise exactly which bulb is out (left or right) is IMO nice, but it may be overkill, and too much to display. Treat each dual filament as separate dual bulbs because that is effectively what they are. BTW - I intended the comparator circuit to be powered only whilst the sensed bulbs are powered - ie, power for the comparator via a diode from each +12V switch. Indicators/flashers might be awkward, but they should not need sensing (the flasher can does that.) Not that the comparator can't be on with IGN (their current is only ~10-20mA as I recall...). One circuit addition may be a "pull-down" capacitor from the comparator's - input (from the bulb) to GND as a power-up hold-down to prevent any false lighting of the LED etc.

that sounds fair..the only problem thats confusing me is that when i think of a comparator its rectangle...not triangle..ive never actually worked with a comparator before..is there a + - leg so i know where to start from? and what about with the quad comparator...it would be the same set up just different legs taking in different lights and going out to different leds?

Download datasheets - eg, for the LM339 - they should show all. And yes, a quad is simply 4 "separate" comparators in one package (4 x 3 pins - 12) with shared +V & GND (hence 14 pin packages).

so if i did pairs on 1 output of the comparator, lets say both back up lights...if one light goes out does that make the sensing led come on saying that one light is out or will it wait for both to go out? the reason having to do it separate is so i know exactly which light is out...setting up pairs i would still have to test to see exactly is it right or left

Usually one failure triggers the tell-tale. Though it could be done "if both", they are usually bulb failure circuits, not "all bulbs failed" circuits".

When I hook this up I take it the 3v out isg going to the led correct? Where is the put for 0v good bulb being hooked up to? Seeing as how I only have one out put for each input...power to the comparator would be 12v I'm assuming

Any input on this? Im ordering the comparators and bread boards so I appreciate, the responses

Sorry, I missed the question. The comparator grounds its output when it is "on", hence the LED's -ve (cathode) end goes to the comparator output. The LED's Anode (+ve) is via resistor to +12V. The 339 can only sink 16mA, so for a 3V LED, I'd suggest a 820 Ohm 1/2W else 1/4W resistor which means a current of ~14mA at ~14V. The 336 operates from 2V to 36V so straight 12V should be no problem - that's good because it allows for the bulb's voltage. If we needed or used a regulated supply - say 12V - then as the lamp's voltage supply changes from 9V (during cranking) to 14V and maybe 15V - that's say 12V +/-3V, or +/-25%, but the comparator's trigger point is from +12.0 regulated and had np such 50% variation... But being unregulated and therefore "tracking" the vehicle's = bulb V-supply, we don;t have that problem. But maybe the 339 needs some spike protection or filtering - I haven't looked at that. But for bread-boarding, so what?    Just buy a spare comparator. (Or are you also budget restricted?) (No decoupling caps are needed - ie, +12V filter caps.) And tie BOTH inputs of unused comparators to the -ve supply, ie, 0V = GND. (From National Semiconductor's LM339 Datasheet's "Application Hints" - even stray capacitance between IC socket pins {and IMO hence breadboard)... "...like most comparators, can easily oscillate...". [ In more detail... "can easily oscillate if the output lead is inadvertently allowed to capacitively couple to the inputs via stray capacitance.". ]