[mRahmani]

Hey guys! It's been bugging me since before I order my car that the Homelink was removed from the overhead console. After way too much time spent looking at diagrams, I've come up with a way to swap in the 2016-18 console without needing to cut into the factory harness, so the car can be put back to stock in the future if needed. The only caveat is that you won't have OnStar buttons in the car anymore... but I doubt anybody on these forums cares about that. Here are the parts you'll need:


Overhead console: There's several part numbers for this, you can find them on eBay or order them new. I have the coupe numbers here, not sure what the convertible equivalents are.

84026942 - Black console with garage door opener and sunroof
84026943 - Gray console with garage door opener and sunroof
84026945 - Black console with garage door opener, no sunroof
84026946 - Gray console with garage door opener, no sunroof


OnStar button: We're going to cut this up to power the garage door opener. GM part number 13440111.

Homelink pigtail harness: ACDelco PT3025 or GM 19300600. This is obnoxiously expensive ($45), but maybe you can get lucky and pull one from a junkyard.

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First thing we're going to do is start making an adapter harness. If you look at the OnStar buttons, you'll see 4 small tabs that hold the plastic case together. Pop these off with a screwdriver and you'll get something that looks like this:




I took a small Dremel and chopped off the board on either side of the 6-pin connector.


Next, take a look at the Homelink pigtail. Annoyingly, all of the wires are white, so you'll probably want to mark them somehow. Here's the pinout for the connector:




Pin 1: +12V
Pin 2: LED backlight
Pin 3: unused
Pin 4: Ground


I snipped off the wire for pin 3 to eliminate some confusion, and marked power and ground with red and black sharpies for reference. You'll want to solder power and ground to pins 1 and 6 of the OnStar connector, like this:





OPTIONAL: Sadly, the OnStar button doesn't have a wire we can use for the LED backlight. Instead, I ran a wire from pin 1 on the passenger side map light button on the new console. If you pop off the plastic cover, you'll get something that looks like this:





You can see where I soldered the remaining white wire from the Homelink harness to pin 1.


My final step was to borrow my wife's hot glue gun and glue the OnStar connector into the back half of the plastic housing. This will allow the factory harness to lock in place properly:





With this done, you can pop out the factory overhead console and slot in the new one. It pulls down from the rear side, with big plastic tabs holding the front side in place. You'll need a small flathead or pick to undo the connectors - there's not much room, but if you're patient they all come out without too much fuss.

This was as far as I got tonight when I ran into a problem I didn't expect: the 16-18 console has a different connector for the passenger airbag indicator than 2019+. For now, I've installed my new console and just left the indicator unplugged, but I'd like to change that in the future.

[mRahmani]

RESERVED FOR UPDATE:

Similar to cutting up a spare OnStar button to make a connector, I'm going to do the same thing with the 2019+ airbag indicator. Here's the parts I'll need to make an adapter harness:

2019+ Passenger Airbag Indicator: GM # 84124320.

2016-18 Airbag Indicator pigtail: GM # 19368127.