Lighting instrument cluster of my truck?

I have an old 1975 Ford F-150 pickup truck. The instrument cluster has little light bulb sockets to backlight the instruments. The plastic of the sockets has broken and the bulbs won't stay in. There are I think 3 small bulbs providing backlighting, then a few separate bulbs for blinker lights, warning lights, etc.

I was thinking it would be fun to take it out and mod it to use LED's, because the bulbs seem to not last very long. If I mod it to LED's I never have to change bulbs again.

I was thinking of putting 2 or 3 Cree XR-E's p2 bin, for the backlighting, and using some bright 5mm LED's for the blinker lights and other idiot lights.

However, with several separate circuits, I could end up in the poor house trying to buy drivers for each. So, can I do this with just resistors? Can someone help me figure out what resistors to use to drive off the 12-14 volts of battery power?

Thanks if you can help with this project! Or if you think it's totally overkill, let me know LOL...

what i suggest is track down the input off all your dashlighing and so on, put on a VDC filter, or diode to take care of any nastys comming into the line. electrical on old trucks are natorious for dirty electrics which will fry and led. then from there you can just run resistors. I suggest using the apporopriate color needed, so u lose less light from the filters. ie, for needles, take a uv light and run it right into it (reacts with the orange), blinkers if u have orange use orange, green use green ect...

I would not recommend running Crees without a driver, but if you must, a 140 Ohm series resistor will give you about 80mA drive current. It won't be very bright, but it would be fairly safe given voltage variations especially in an older vehicle. Most 5mm's with a Vf of 2 will run with a 440-600 Ohm series resitor on 12-14V. however You will still need to connect a zenner diode to protect the LEDs from reverse voltage spikes, otherwise you will replacing LEDs just as often an lamps, if not more so.

Dang I didn't realize it was that complicated with the voltage problems!

OK what about this... zenner diode and resistors for the idiot lights and such, and I buy some kind of driver for the backlighting Cree LED's?

What driver woudl you guys suggest for using in a car, something that won't get ruined by the voltage spikes and such, and will make my Cree's shine bright?

I think a pair of Luxeon V would give you pretty good use in series with a low current drive or a resitor.

Well the reason I was attracted to the resistor idea is, the truck has a dimmer for the cluster lights, and I think if I use a resistor for the backlighting, the dimming would still function, whereas if I use some kind of regulated driver, I'm thinking the brightness would stay the same even if I turn down the dimmer! isn't that true?

Should I just use an assload of 5mm white LED's instead of cree or luxeon, for the backlighting, and resistors on them, + a zener diode for protection?

I don't think back lighting bulbs need to be very bright otherwise they will interfere with your night vision. I doubt you'll be needing more than a couple of ultrabright 5mm's.

Really? well maybe I'm totally off on a tangeant here... maybe I should just drill a few holes in the back of the cluster box and superglue in some 5mm led's, wire 'em up, resistor and zener diode, and call it good lol... Whatever I do is gonna look sweet though compared to the stock bulbs, they are very dim...

here is what you can do. put a zener diode before your PWM circut some premades kits can be found on here, then get a have the dimmer adjust the pwm. then ur set to go. but if you are just looking to get brighter, you just may wanna put new high output bulbs in if cost is of issue. right now i think u are looking at 40-70 bucks to do the led conversion.

Hellbore said:

Really? well maybe I'm totally off on a tangeant here... maybe I should just drill a few holes in the back of the cluster box and superglue in some 5mm led's, wire 'em up, resistor and zener diode, and call it good lol... Whatever I do is gonna look sweet though compared to the stock bulbs, they are very dim...

Click to expand...

That'll work. I think an XR-E would be waaay overkill for back lighting. Connect the zenner in parallel to the LED and in the opposite direction, the resistor in series with that assembly. You should be able find all the parts at Radio Shack, unless you want really bright 5mm's, in which case you can probably get Nichia's or SMJLED's or THC's from the B/S/T or vendors' forum here.

If you have a search on eBay, there are plenty of replacement LED bulbs for car back-lights, sidelights, brake lights etc etc. I'm sure that you'd find a direct plug in replacement.

Well a direct plug in replacement isn't gonna be much easier, if at all, because the socket it would plug into is broken. If the sockets weren't broken already I might just put bulbs in them and call it good. SINCE I can't replace the bulbs without doing some kind of a repair job, I figured I might as well put LED's in there.

Something else to consider -- in some older vehicles if the bulb blows it might cause a rise in the resistance along any other lights on the same circuit. That can cause more bulbs to go even if the sockets are in good shape. It might be a good idea to get a Ford service manual with a wiring diagram and see what else is on the same circuit. Replacement sockets are available but I don't envy anyone who has to rewire a dashboard of any car made after about 1967. Trust me, it's easier to remove the entire dash and go at it from outside the truck. Good luck whichever way you tackle it.