[HOW-TO] "4-HI" brake light mod (EASY method!) (STOCK TAILS)

[jdyates]

I did this and a writeup for this in 2004 on Chevytruckworld and Fullsizechevy. I modded my circuit boards to light bolt filaments and added an upper and lower 194 marker bulb to mimic the 2003+ Silverado tails.

I did mine to a set of 88-89 tails with the 1157 bayonet based bulbs. It's not as easy as the 90+ trucks with the 3157 wedge base bulbs. I had to remove a strip of materal down the side to fit the wire between the bulb and socket. After all said and done, I had a good deal of problems with them because of the additional heat. The 88-89 circuit boards are garbage because of the bayonet based bulbs. I switch to 90+ style circuit boards and did the same thing as Joesph did above, and after about a year had problems again. In 2007 I was fed up and cut the OEM plug off and used individual sockets like the GMT800 trucks use, and held them in with a piece of plumber's tape. Haven't had a problem since.

My original threads no longer have pictures; at some point they went the wayside with a failing hardrive and the forum they were hosted on no longer has them.


Having done this mod myself, and had it for a LONG time, I would not suggest it on the OEM style circuit boards; I personally had too many problems with the boards messing up.



If anyone is interested in seeing the GMT800 sockets on my truck I could get a picture of them.

I've seen them. They look great. I've thought about modding the harness too but i couldn't think of how i would hold the bulbs in place. Although, I'm curious as to how the boards messed up? It would make sense if you modded the board itself, but this way you don't mess with the stock contacts at all, since there are no contacts to begin with in the top socket for the high filament. You are just running power to it, not modifying the board.

 

[88GMCtruck]

What have you seen? I'll have to get pictures of my setup, I have posted pictures of the gmt800 sockets before.

The oem circuit boards fail from the additional heat. The 88-89 ones are way worse, but the newer ones do it to. Not everyone has the problem, but there is a reason you can go to the parts store and buy the circuit board in the "help!" section.

Out of my two gmt400 vehicles I had problems with both. My best friend had problems with his as well. Neither my 99 or my buddy's 98 were molded. The way the boards are designed they can intermittently fail over time, from what I think is heat.

That is why I do not think it's a good idea to not mod them this way.

Sent from my big block powered HTC gas guzzler.

 

[jdyates]

What have you seen? I'll have to get pictures of my setup, I have posted pictures of the gmt800 sockets before.

The oem circuit boards fail from the additional heat. The 88-89 ones are way worse, but the newer ones do it to. Not everyone has the problem, but there is a reason you can go to the parts store and buy the circuit board in the "help!" section.

Out of my two gmt400 vehicles I had problems with both. My best friend had problems with his as well. Neither my 99 or my buddy's 98 were molded. The way the boards are designed they can intermittently fail over time, from what I think is heat.

That is why I do not think it's a good idea to not mod them this way.

Sent from my big block powered HTC gas guzzler.

I've seen the picture with both 194s modded it. Also, I've had the same circuit boards since i've owned the truck. They look very old (probably not original, though. lol). So if they do decide to fail, they will now with the additional head. We'll see i suppose. They are cheap enough to go grab a new one/both from the parts store (which you are right about, both O'reillys in my town have them on the shelves). I'm going to be putting LED bulbs in them soon, maybe that will fix the heat problem.

 

[Crash]

Thanks for post this with good pics, just did it.

 

[Dszx13]

Just did this aswell. Took 5 minutes an a little bit of wire. A must for any one with tinted tail lights

 

[jdyates]

Just did this aswell. Took 5 minutes an a little bit of wire. A must for any one with tinted tail lights

Definitely. Keep an eye on them, though. If you didnt get a wire in far enough, it will wiggle loose and look like you have a bulb out if you hit a bump hard enough.

 

[AirmanSkee]

About to go do this to mine. Completely forgot about this one! And once my new corners come in (after this damn GOV shutdown) I will do the 4 corner mod up front.

 

[1997k1500Calvin]

About to go do this to mine. Completely forgot about this one! And once my new corners come in (after this damn GOV shutdown) I will do the 4 corner mod up front.

You have a link to the four corner mod?

Sent from my HUAWEI H881C

 

[1997k1500Calvin]

Any reason why my brake lights won't work?I replaced my switch and bulbs...reverse and running lights work fine

Sent from my HUAWEI H881C

 

[jdyates]

Any reason why my brake lights won't work?I replaced my switch and bulbs...reverse and running lights work fine

Sent from my HUAWEI H881C

Switch has to be adjusted and clipped on both the pedal AND te metal piece next to
It.