What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

who's still running sealed beam lights?

colbystephens

colbystephens

1 ton status
GMOTM Winner
Joined
Feb 24, 2005
Posts
10,967
Reaction score
125
Location
Oregon
b/c you shouldn't be. i went to the parts store today and picked up a set of bulb housings and a couple of 9003 light bulbs. installed those suckers and holy crap! what a difference! i can see that my headlights are on now. totaled 40 bux - that's better than one light for a hella conversion! :)

got a question tho - now that i've got a couple of 9003 lights in as my low beams, they seem to be taking all the power such that when i turn on the brights, they don't do more than turn the filaments on those bulbs orange - the light is hardly there, but the low beams are just as brite as before. do i need to re-route my wiring? it would seem from the response to these new more powerful lights that the lights are hooked up in series, but surely that can't be the case b/c i've run with a light out before, and all the others still worked. what's the deal?
 
Do the relay mod...

modifiedrelaycircuit9hu.jpg
 
I don't know about anyone else but i wouldn't trade my little 89-91 model lights for anything, they're brighter then alot of new cars.
 
I agree with the relay mod. I put the relays on before I went to H4 housings and 9003 bulbs. Only had 12.5v at the lights when the alternator was putting out 14.3v. Dropping that much voltage is what makes the lights dim. I know with just the relays and old halogen sealed beams the light output was at least twice of what it was. Add in the H4's and now it has an insane amount of light output. It's amazing what 14 volts to the headlights do for the brightness.

On th subject of your wiring being changed, unless you did something to it in the conversion from sealed beams it shouldn't have changed. The stock headlight setup is a parallel circuit. this way if one bulb goes out, the other stays lit. Your poor output now is most likely due to low input voltage at the bulbs and or bad grounds at the lights.

THe stock circuit is prone to high voltage drops. Think about it this way, power flows from the battery, through the junction block on the firewall, Fuseblock, then to the headlight switch, then to the dimmer and finally back through the firewall to the lights. The resistance of the wiring plus the switches takes a little bit of voltage and by the time you get to the lights you have less to work with. It's just not efficiant at all. This is why the relays work so well. They allow the stock wiring/switches to just turn on/off the relays that have power coming right from the battery/alt.

LMC sells a kit to do this also that requires no cutting of the stock harness. Just unplug the old lights, plug the new harness to the lights, add power/ground to the relays and plug one of the old headlight sockets into the new harness for the input from the switch. Really easy to install but the power feed circuits to the relays have NO FUSE. If you use the system, add a 30 amp inline fuse holder to each power feed circuit (2). If you don't and you have short, the wiring (and possibly the truck) will go up in smoke.
 
colbystephens said:
b/c you shouldn't be. i went to the parts store today and picked up a set of bulb housings and a couple of 9003 light bulbs. installed those suckers and holy crap! what a difference! i can see that my headlights are on now. totaled 40 bux - that's better than one light for a hella conversion! :)

got a question tho - now that i've got a couple of 9003 lights in as my low beams, they seem to be taking all the power such that when i turn on the brights, they don't do more than turn the filaments on those bulbs orange - the light is hardly there, but the low beams are just as brite as before. do i need to re-route my wiring? it would seem from the response to these new more powerful lights that the lights are hooked up in series, but surely that can't be the case b/c i've run with a light out before, and all the others still worked. what's the deal?
Click to expand...
got any part #s?
 
thanks for the suggestions regarding the relay mod. just to reiterate: this mod would allow enough power to be sent to both sets of lights - right? i see the wiring diagram, and i understand it for the most part, but i don't really know why/how it's different from stock. is it a diagram of what i need to do?

here's how i read it (is this right?): i need to have four wires running from the alternator (how do i decide on a wire guage?) - one to the battery, and one to each of the three relays pictured each being intercepted by a 30 fuse. (What do the numbers mean on each relay, and how do i know which type of relay to buy - if there's an option?) then i would run wiring from the identified relays directly to the beam selector (I have the floor-mounted beam selector - does this cause any problems with this mod? How will i determine the high out put wire versus the low?)

What do the black wires which come off the negative battery terminal and the lights go to? are these just grounds?

So, how's my interpretation? doesn't look too complicated except for wiring up the switches in the cab - particularly because of the floor mounted switch.


Any thoughts about wiring for the other lights i was talking about?

BBlaze: i don't have part numbers, for the most part. I don't know how your last generation head lights are set up, or if it will help. all i know is that on mine, i couldn't see that my headlights were on, and only barely noticeable on dark roads - which i tend to drive alot. for me, it meant going to the parts store, picking up a lense which you can install a bulb into (versus the original style where if your light goes out, you have to replace the whole unit - lense and bulb). The light bulb is a 9003. The headlamps should be with all the others on a shelf - look for your appropriate size/shape, pick out a bulb and you're set. it plugs into the existing wiring.
 
do you have any pics?
I see you have the 4 headlights.. like I do..

I have a 1978 truck with a 1987 front clip....
 
I bought a kit for the relay mod. Comes with everything you need w/harness. It was $30. Could buy seperately for cheaper but I figured the ease of installation & prewired harness was worth the money.;) I think I got it from a vendor here:wink1:
 
another way...

I've seen guys here get those headlamp housings out of cars at the junkyard and swap them into our style trucks...I think some BMW's use them factory..other foriegn cars too..

I'd like brighter lights,but have too many other things that need attention on my truck first..seems like a lot of wiring adding in 2 relays...

But it would be nice to just be able to swap in a new headlight bulb in seconds,instead of having to remove a bunch of trim around the lights,and use a torch to heat the retaining ring screws up,so you'll have a prayer of getting those screws out!..I think the 9004 bulbs were THE best invention on vehicles the past 20 years!--but not much else do I consider "better"..

I'm considering adding a pair of driving lights that are wired separately from my headlamps..my headlights acted up on my 82 K20 last week--had to get a ride home,they refused to work!--thought I fixed them,then last night they went out on a road with NO streetlights--guess my dimmer switch or its wires are corroded,I cleaned them,but dont trust them now!..I think having 2 more lamps as a back up wouldn't be a bad idea!.. :crazy:
 
the light fixtures i bought have a day-time running light included - just gotta wire it up.
 
colbystephens said:
here's how i read it (is this right?): i need to have four wires running from the alternator (how do i decide on a wire guage?) - one to the battery, and one to each of the three relays pictured each being intercepted by a 30 fuse. (What do the numbers mean on each relay, and how do i know which type of relay to buy - if there's an option?) then i would run wiring from the identified relays directly to the beam selector (I have the floor-mounted beam selector - does this cause any problems with this mod? How will i determine the high out put wire versus the low?)

What do the black wires which come off the negative battery terminal and the lights go to? are these just grounds?
Click to expand...

Colby, you might be overthinking it just a tad. This is a really simple modification. Let me run though your questions one at a time:

4 wires from the alternator? Not really. The schematic posted is really simplified and includes wiring you already have (including the switches). So no you won't have 4 wires pulled from the alternator. I actually pulled my power from the junction block on the firewall just to the left and above the p/b booster. (it's diamond shaped with two studs with wires going to each) That block gets fed power right from the alternator and it's an easier place to put a new wire to than piggybacking a bunch of wires to the output stud of the alt.

I used 14 gauge wire to run power and grounds to the relays.

Relay's. I used relays rated for a 30 amp load. you can find some with lower or higher, but I wouldn't run less than ones rated for 30 amps. Numbers on the relays relate to inputs/outputs of the relay itself. #30 is power input (high current), 86 is low current switched input, 87 is high current output and 85 is ground.

then i would run wiring from the identified relays directly to the beam selector ? No. You are using the stock wiring here as the switched input to the relays. On my truck (75 k5) there are only two wires running from the floor mounted dimmer out to the drivers side light. At the lamp connector, those two wires come in, but two are also there that lead to the pass side light. SO, if you cut the high/low beam wires leading into the driver's side bulb from the dimmer, you can take the side from the dimmer and put a terminal end to connect each to the 86 terminal of the respective relays. The side cut to the lights, you put terminals on and connect to terminal 87 of the relays (high and low).

The simple version is, the only wiring you need to add is power circuits to the relays and ground to the relays. Cut the high/low circuits on the input side to the driver side bulb, add terminals and connect them to the relays. Mount the relays and you are done.

Here's a link to an article I wrote for another site, that another person contributeted a different schematic to:

http://www.73-87.com/7387garage/exterior/headlight_relay.htm
 
I installed a set of sylvania white light sealed beams on my 94 c1500. Big difference. Think they may be marketed under the silverstar name.

I've also done the relay thing on my 87 and I am going to do it to the 85 as soon as I find the time. I use relays from a GM starter harness recall for the 96-98 grand ams. Comes with a relay and a sealed connector. Price was about $17-20 per relay with the pig tail on it. I don't have part numbers handy, but the 4 cyl kit (~18-24 inches) has a shorter harness than the 6 cyl kits (~36 inches). A decent parts counter guy/gal should know the part number off hand.
 
You could use a diode on the high beam relay to control your low beam relay when the highs are on. That way it would not feed back when only the low beams are on and it would remove the third relay.
Daniel
 
On k5's with quad headlights, (81-88) the high beams get the power from the low beams. You could use just one relay to power the whole thing. I used two, one per headlight. I use the original wiring to power up and control the relay.
 
thanks AZ79K5Project. i made my own headlight relay kit already. i shoulda said something about part #'s for the bulb housings that colbystephens bought for 40 bux instead of just replying with +1.

colbystephens, what parts store did you buy these bulb housings? inquiring minds want to know.
 
You must log in or register to reply here.

Latest Posts

Top Bottom