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C5 Homelink Install

Vehicle Information: 2001 Corvette Coupe. This writeup would work for almost any vehicle. You should have a basic understanding of electronics, as well as have a good soldering iron for attaching the wires to the printed circuit board within the homelink transmitter.

If this writeup sounds like it was written in a foreign language, maybe this install is not for you. On the otherhand if some simple wiring and use of a VOM is second nature to you, then have at it!

Let us know what you think via email, or on Our user names on there are 'Sliebl' and 'Janster'.

Although this fix can most likely be used for any car, your application may have subtle differences not shown in these pictures. Use our write-ups at your own risk. Please don't attempt these fixes if you aren't atleast mechanically inclined. We take no responsibility for damage that may result from the use of our write-ups.

Parts and Tools Required:
Homelink Transmitter from a sun visor. Note: These can be found on eBay or any junkyard. Do a little research and make sure you get one that is compatible with the 'rolling code' garage door openers, even if you don't currently have one of those, someday you might.
Small piece of fiberglass perf board, or other similar board to hold the switches and LED.
3 - SPST Tack Switches. I used part number 642-MJTP1230B (about $0.16 each). Note: You can use any SPST buttons you choose. As long as they are Single Pole/Single Throw, Momentary, Normally Open buttons.
1 - Red LED - standard polarized LED, sorry no Part #.
Length of Ribbon cable, atleast 6 conductors.
Wiring to attach the transmitter to +12V and Ground.
Tap-In connectors
Soldering Iron and Solder.
Silicone RTV
Several different drill bits, and associated hardware to attach the remote 'button board' to the car.
Dual Lock (Plastic Velcro from Radio Shack - SUPER STRONG!)
Other Misc supplies as noted with the pictures.

Difficulty Level: I'd give this a rating of 3 out of 5 with 5 being the most difficult mods, and 1 being an oil change. The actual install is not difficult at all... about a 1 or 2 on my scale. Wiring up the transmitter will take some finesse, especially if you don't have any electronics experience, therefore the elevated difficulty level.
Click any of the small photos for a larger version.


Step 1: Open Homelink Transmitter

You need to remove tear the transmitter out of the visor. Mine came without a visor. $45 on eBay, but they can be had cheaper if you shop around. Once you open the case, you will see the three surface mount tack switches, as well as the surface mount LED (removed already in my pics). I made a notch in the side of the case for the ribbon cable to fit through. You also don't have to use the ribbon cable. Standard 20 or 22ga wire would work fine. I used what I had on hand since I work for an electronics contract manufacturer, these items were easy to source from scrap boards.

Don't forget, you can click any of the pictures for a larger version to see more detail.


Step 2: Close Up of Wiring

With a standard VOM, you can quickly determine which side of the push buttons is common between all three buttons, and which side is the 'signal' side. The red wire in my setup is the common wire. Only one attachment is necessary. There are only three other wires required for the push buttons, one for each switch. Pressing the button makes the circuit between the 'signal' side and the ground, lighting the LED and opening the door. The other two wires at the bottom of the PC board lead to my remote mounted LED. It will only light one way. If it doesn't light, switch the wires at one end.

Not shown: RTV the Cable where it exits the case. This will prevent the delicate solder joints from being damaged if the cable is pulled on.


Step 3: Make a board to hold your buttons

This board is 0.1" perf board. There are holes every 0.1" in each direction. Perfect for this job, as the switches I had were 0.2"x0.3" spaced, and my LED is standard 0.1"

I mounted the switches and the LED to the board by tabbing the legs of the parts on the back side. I also added a drop of CA glue (superglue) to each part on the top side of the board, just as a precaution since the parts aren't soldered to the board.

You can lay out the switches any way you choose. You might even just want one button to open one door. Possibly a panel mount button that would nut directly to the console. Just note that you need atleast the outer two buttons to go through the Homelink programming. This can also be done with the original buttons as they remain totally usable.


Step 4: Back Side of the Perf Board

Note: Each switch has four leads, two on each side are common with one another.

On the left edge of the board you can see where I joined three leads together. These are common between each push button. I also attached the red wire (top of the ribbon) to another common point on one of the switches. This ties all commons together. The next three wires are attached to the opposite side of each switch. The last two wires were attached to the LED. Again, if it doesn't light, reverse the two wires. I used an LED checker to determine which side of the original LED was the cathode, and did the same for the remote LED.


Step 5: Hole Drilling Template

Using the perf board for mounting the switches also has the benefit of having an easy to make drill template. I just drilled out the holes using the predrilled 'pilot' holes. Perfect fit! I also drilled two smaller holes for some 2-56 hardware.
I also attached a few thicknesses of perf board to the top side of the button board to get the proper mounting depth. You could also use some 1/4" spacers or washers. Mount the button board with 2-56 hardware or whatever means you choose.


Step 6: POWER!

Where I mounted the button board gave me very convenient access to 12V unswitched power (on all the time). I just used some wire 'tap-ins' from Radio Shack to apply power to the leads from the Homelink Transmitter. You only need 12V+ and Ground. Simple. You can also see in this picture where I hid the transmitter. It's Dual Locked (plastic Velcro) to the underside of the forward console. Just out of sight in the picture. The power can be easily unplugged from the transmitter if I need to pull the console out in the future. You can also see the loop of ribbon cable that I have left over since I didn't know exactly how much I'd need... I obviously went a bit overboard. 8" would have been plenty. It's hard to see, but I wrapped some split loom wire guard over the end of the ribbon as it passes through to the rear console. (It's under the 12V outlet in this picture).


Step 7: From This Bulky Nonsense!


Step 8: To This!

Slick hidden install, and I don't have to worry about someone snatching my garage door opener.

I hope you found this write-up useful.