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GMT400 Headlight Mods

20K views 14 replies 6 participants last post by  Shackleferd  
#1 · (Edited)
One of the best mods we can do to our trucks is the 4 high mod, with the use of a relay when you turn your highbeams on the relay is triggered supplying power directly from the battery to power the low beams back on. lighting up the road ahead of you so much better.

thanks to a great idea from @kennythewelder I took this one step further by supplying my low beams when on by themselves with a relay directly from the battery. basically you cut the supply wire, the feed that goes to the lights is connected to the output of the relay. the main supply feed is connected to the trigger side of the relay. the ground is connected to ground and your positive feed is connected to the battery. when you turn the lights on it triggers the relay which then powers the lights directly off the battery. doing this makes them like 5 times brighter!

Combining that with a headlight restoration or better yet new lenses and a headlight alignment really brings these old headlights back to life and probably way better than when the truck was manufactured.

you can buy these relay kits off ebay for about $20, other auto parts stores for a lot more or you can roll your own for a fraction of the cost. relays are cheap but I prefer the $20 ebay kit myself because its already built, includes a fuse, the wires are decent and cut to the length for our trucks. just dont use the blue wire taps, throw those in the garbage then solder and shrink wrap everything for a permanent connection.

I just installed a brand new set of glass lenses on my truck, I did restore my lights about a year ago but one of them couldnt be propely aligned because the mechanism was broken. I used washers behind the housing to get it pretty close but I wasnt satisfied. so now on to my new glass lenses!

Al

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#2 ·
Few things are worse for a driver at night than bad headlights. I'm glad you were able to upgrade and enjoy your passion (suburban) even more.
 
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#3 ·
your darn right! I cant believe I drove my truck for a year with yellow oem lenses. I always struggled at night to see the road ahead of me. it wasnt until one very foggy night that I realized just how bad they were, one of my beams was headed up to the right never touching the ground, that was when I started researching headlight upgrades and found out about the 4 hi mod.
 
#4 · (Edited)
There are many relays and relay kits available on ebay, searching for them brings up 1000's of options. This kit here is the one I purchased and used when I rewired my lowbeams.

http://m.ebay.ca/itm/302121113140

The seller was excellent to deal with and the kit is built perfectly for these mods.

Heres a Canadian seller, I used this kit on my first mod, he just didnt have any available when I needed the second one otherwise I would have used him again. Same thing, great product and a great seller.

http://m.ebay.ca/itm/4-BEAM-HEADLIG...DLIGHT-MOD-KIT-88-98-CHEVY-GMC-FULL-SIZE-TRUCK-KEEP-LOW-BEAMS-ON-/232256244200?

Al
 
#7 ·
The harness is fine. But one of the bulbs plastic mounting tabs needs to be clipped a little...

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The high beams both burned out on my wife's Lexus RX350. I was surprised to see my old Chevy and Lexus both used 9005s, so I ordered 4 9011s. The Lexus takes them without the trimming, but the Chevy needs a pair of side cutters taken to them. I have some 9012s for the low beams on the way, they replace the 9006 and require the same trimming.
 
#8 ·
Out of curiosity, what makes these bulbs better than oem when they are the same wattage? If they are better I want them since they are the same wattage and dot approved then they are legal... just curious what makes them better?

THANKS!

Al
 
#9 ·
Third Generation Halogen Infrared (HIR) - HIR1 ( 9011 )

The 3rd Generation 9011 (HIR1)Halogen Infrared Reflective bulbs are among the most efficient halogen headlight bulbs in existence. The first commercial application was the high beam of the first-generation Dodge Viper, then in the low beam of the 2003 Nissan Maxima's high/low beam lamps, and since then they have been specified as original equipment in a wide range of vehicles, off-road equipment, and snow plows.

Toshiba, which was formerly the primary supplier, no longer makes these bulbs. They are currently manufactured to OE quality and performance specifications by Philips, Vosla, GE, and Osram. We supply Vosla, Philips, and Osram HIR bulbs. As with all bulbs, the design varies slightly depending on the manufacturer. It's most productive to focus on the bulb's performance, not on its design details. For example, there's a rumor on the internet that the Toshiba bulbs were "real HIR bulbs" and the Philips bulbs aren't. But our objective testing shows the Philips product running 10.8% brighter than the Toshiba.
 
#12 ·