CK5
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Headlights
- Thread starter FatBoyM
- Start date
What year/style headlight?
Square 1985 blazer Silverado
There’s a few options depnding on what what you want. If you want to keep the oem look, you can get some good sylvanias or the like and upgrade the harness with relays. That helps quite a bit with the voltage to the lights.
If you’re not against the look of led’s there is plenty of options there.
If you’re not against the look of led’s there is plenty of options there.
Sometimes just replacing the headlights with basic new ones can make a difference. They get dimmer over time.
Personally, I always go with the Silvania XtraVision lights. They work fantastic, imho. They are very affordable too.
Personally, I always go with the Silvania XtraVision lights. They work fantastic, imho. They are very affordable too.
Haven't checked for a couple years but I think it was holley that was making LED's that look stock unlike the ones I'm running, which are Philips. The Philips work very well, but visually you can tell they are LED's even when off.
LED's can also be terrible in snow if that's a consideration.
I converted mine to run all four lights in low and high after that day, with the bottom pair remaining halogens to make sure I've got some light if it happens again.
LED's can also be terrible in snow if that's a consideration.
I converted mine to run all four lights in low and high after that day, with the bottom pair remaining halogens to make sure I've got some light if it happens again.
J.w.speaker .
I posted a threads worth of info on all my trucks led upgrades in the garage section . Go find it .
I posted a threads worth of info on all my trucks led upgrades in the garage section . Go find it .
I would definitely go for two major changes tha others have mentioned. One, regardless if you stay incandescent or go led is the wiring. The stock harness has the circuit going all the way from the battery to the bulkhead/fuse panel, to the headlights switch and hi/lo switch then back through the firewall and finally out to the light on the drivers side the the passenger.
The issue here is voltage drop. Just check the voltage at the light with the truck running and the lights on. You are going to see something like 12v or even less even with the alternator pushing closer to 14-14.5v. Old wiring will have a little higher resistance, but the circuit design itself is why it drops so much.
Modern vehicles for close to 20 years use relays in the headlight circuit to maximize the voltage available to the light by reducing the overall length of the power circuit to the lights from the battery.
Multiple ways to do it. Easy, order a headlight relay harness from LMC truck. Unplug the stock harness from your lights, hook up direct power for the relays (make sure they are fused, early kits were not, I think they are now), hook up the grounds for the relays and plug in the new sockets to your bulbs. Done.
Painless wiring also makes a universal kit that you can modify to work. Or make your own. Use a couple of relay with pigtail kits from Amazon or other suppliers on line. Go to the driver side bulb and unplug the stock harness. You’ll see the socket has two green wires to one terminal and two tan wires to the other terminal and the last should be the ground. If you trace back from the plug you’ll see singleton and green wires going over to the pass side light and the other two green and tan wires going back down the fender to the bulkhead.
The bulbs are set up as a parallel circuit with separate grounds. Give yourself some length back from the drive side socket and cut the green/tan wires. The two wires coming from the bulkhead are now the “on” signals for the two relays and the two wires leading to the driver side socket are going to be the power feed from the relays. Splice those two to each respective terminals on the relay pigtails. Put a ring terminal on each of th relay ground circuits and then using an inline fuse on each of the power circuits from the battery or junction block to the power circuits on the relay pigtails
You really don’t have to know which circuit is high or low as long as you connect the same color wire (green or tan) to the same relay.
With relays installed however you did it with a kit or diy if you measure voltage at the light you’ll see now the drop is like 2-3 tenths of a volt vs a couple of full volts. This alone will make low beam on an incandescent bulb closer to what the output was on the high beam without the relay. Highs are a lot brighter. If you decide to go led they will work even better with proper voltage.
I’m running generic h4 conversion housings for the big square bulb my truck uses. Not as nice as JW Speaker but still have decent optics without looking to alien bug eye style. Holleys retrobrights are an option, albeit a spendy one. Quake LED has some similar looking replacement housings with glass fluted lenses that look closer to stock sealed beams for a way better price than Holley. I’ll probably use those when I need to replace my housings.
Don’t forget to properly aim those lights after you are done. What’s the point of all that light output if the driver side is pointed right at oncoming traffic and the passenger side is lighting up the trees on the side of the road.
The issue here is voltage drop. Just check the voltage at the light with the truck running and the lights on. You are going to see something like 12v or even less even with the alternator pushing closer to 14-14.5v. Old wiring will have a little higher resistance, but the circuit design itself is why it drops so much.
Modern vehicles for close to 20 years use relays in the headlight circuit to maximize the voltage available to the light by reducing the overall length of the power circuit to the lights from the battery.
Multiple ways to do it. Easy, order a headlight relay harness from LMC truck. Unplug the stock harness from your lights, hook up direct power for the relays (make sure they are fused, early kits were not, I think they are now), hook up the grounds for the relays and plug in the new sockets to your bulbs. Done.
Painless wiring also makes a universal kit that you can modify to work. Or make your own. Use a couple of relay with pigtail kits from Amazon or other suppliers on line. Go to the driver side bulb and unplug the stock harness. You’ll see the socket has two green wires to one terminal and two tan wires to the other terminal and the last should be the ground. If you trace back from the plug you’ll see singleton and green wires going over to the pass side light and the other two green and tan wires going back down the fender to the bulkhead.
The bulbs are set up as a parallel circuit with separate grounds. Give yourself some length back from the drive side socket and cut the green/tan wires. The two wires coming from the bulkhead are now the “on” signals for the two relays and the two wires leading to the driver side socket are going to be the power feed from the relays. Splice those two to each respective terminals on the relay pigtails. Put a ring terminal on each of th relay ground circuits and then using an inline fuse on each of the power circuits from the battery or junction block to the power circuits on the relay pigtails
You really don’t have to know which circuit is high or low as long as you connect the same color wire (green or tan) to the same relay.
With relays installed however you did it with a kit or diy if you measure voltage at the light you’ll see now the drop is like 2-3 tenths of a volt vs a couple of full volts. This alone will make low beam on an incandescent bulb closer to what the output was on the high beam without the relay. Highs are a lot brighter. If you decide to go led they will work even better with proper voltage.
I’m running generic h4 conversion housings for the big square bulb my truck uses. Not as nice as JW Speaker but still have decent optics without looking to alien bug eye style. Holleys retrobrights are an option, albeit a spendy one. Quake LED has some similar looking replacement housings with glass fluted lenses that look closer to stock sealed beams for a way better price than Holley. I’ll probably use those when I need to replace my housings.
Don’t forget to properly aim those lights after you are done. What’s the point of all that light output if the driver side is pointed right at oncoming traffic and the passenger side is lighting up the trees on the side of the road.
Dude!
Thank you. This is very informative & caters to my ignorance of Rookie owner.
I really appreciate the effort & details. I'm going to try the 1st (simple) way, since I'm new to this. I may reach out again because I'm a rookie.
Thank you. This is very informative & caters to my ignorance of Rookie owner.
I really appreciate the effort & details. I'm going to try the 1st (simple) way, since I'm new to this. I may reach out again because I'm a rookie.
Don’t sweat it. We all had to start somewhere I had help early on too. Shoot I’m still learning on some things. We like helping around here in general so don’t hesitate if you do have more questions.
I've noticed that, little different when I first joined the Harley forums decades ago, it was a little intimidating.. Just took time to find the right people. Here it's much more kick back from the get go. Even if a lot of it is over my head.
We play nice here . .
Ask away before you spend your money the wrong way . Learn from us who have .
So true !
Good bunch of knowledgeable knuckleheads on here and our tastes in rides range from bone stock to almost full on rock-buggy type builds.
You will get good input on every type and level of what you’re working on no matter how basic or wild you end up going with for your K5.
We may not all agree on certain parts for every application but there’s no real argument presented - this is a good thing though; it allows coverage of many options and paths for whatever the topic is.
In the end you will end up with very accurate and reliable information and not just one guy’s opinion - there’s a bunch of GM truck forums out there but there’s a reason we all mostly setup camp here.
Do you have any experience/evidence that the LEDs are brighter with upgraded wiring? For one thing, unless you're going huge on light output, the LEDs will draw less current, which means less voltage drop. Secondly, pretty much every LED bulb will be running in current regulation, which should make the light output the same over some range of input voltage.
On the one hand, using relays takes almost all of the load off your in-cab switches, so they can live longer. On the other hand, adding more parts is more points of failure.
The led world is not as sensitive or draw the amps like old bulbs did.
But the upgrade is still good to do even for safety of wiring .
But the upgrade is still good to do even for safety of wiring .
I’d say the leds were brighter on my old S10 that I had swapped in blazer composite housings. I had been running incandescent bulbs, changed to led and did the painless universal relay harness last. The leds did get brighter but I had no way to quantify how much brighter they got. It was probably not as noticeable as the difference in brightness on incandescent bulbs before and after adding relays but it was brighter with leds.
Honestly the only added bits would be the relays, inline fuses and some wire. Not a ton to go wrong. Over the time on my diy harness on my ‘75 I never killed a relay. I was running some pretty hot H4 bulbs that was probably pushing the relays as far as current draw and still didn’t have a failure. The S10 painless harness only experienced a failure due to my failure to secure the harness over the radiator support. Still no relay failure but the harness got mangled in the fan.
My ‘91 is using a LMC harness that was originally setup for a quad headlight setup that I never used when it was a quad headlight truck. Mainly due to the fact LMC’s harness for the quad headlight 89-91 trucks does not use the same headlight plug as the factory bulbs. It’s a crappy ploy to force you to buy LMC’s quad headlight housings. Screw that. So my LMC harness was modified to go with the dual headlight setup I put on my ‘91. That’s been a while it’s been on my truck and zero issues with the relays or led bulbs. I do carry a couple extra relays just in case in the truck.
I have the LMC harness and have used multiple sets of LED headlights and I still get some flickering, Im tempted to go back to regular headlights.
I’d look at different led bulbs before going back to incandescent. Cheap ones can flicker but quality ones typically don’t. It’s usually the driver inside the bulb that causes the flicker.
I’ll never go back to incandescent on my stuff. The only car in my fleet that still has incandescent is my ‘57 and I’ll probably swap LEDs in before I take a long road trip with it. My Dad swapped in European Cibié 7” round housings that used H4 bulbs. Those have been on the car since he bought it in the 70’s and are decent but still not enough for me to be comfortable at night.
Look at Arc Lighting for some serious bulbs. Race sport are good too at a little better price. I’m running race sport bulbs in my S10 and TBSS. They have been working well in both and I’ve had the in there a couple of years with zero issues, no flicker or any other problems.
I've tired different bulbs and housings. I'll check out your recommendations.
