jrmdir

I added a HomeLink unit to another vehicle and have been researching adding one to my ’96 C2 - and needed it to be remote mounted. There are a few threads out there on this. I was leaning toward the “add a 6th switch to the console” plan, but two things held me back: a) OEM switches are not cheap and, b) I’m lazy - mounting things under the dash and messing with the console wiring harness is not my idea of fun. But procrastination paid off – after a lot of thinking I came up with what – to me - seems a perfect solution:

• Complete invisibility: no in-cabin mods whatsoever
• No cutting or drilling
• No taping into or splicing the wiring harness
• No new Porsche parts to buy
• Plug-in installation
• Finger-tip operation
• The mod can be 100% reversed (no trace) in less than 90 seconds – really!

The trick is to hijack the steering column switch and wiring - from perhaps the most un-loved feature on our cars – the headlamp washers! I’ve posted some photos below and will be happy to post more details, but here’s an outline of the project for any who are interested:

Obtain a HomeLink unit from eBay or junk yard (I got 2 for $10 at a pick-n-pull yard). Get one of the small ones – those that were built into sun-visors. Mine came from 1999 and 2000 MY cars. There are just 2 wires: +12 and Ground. Hook them up temporarily and program one of the three buttons to operate your opener. Then disconnect the power and find a way to permanently or semi-permanently hold down that button. Here, I popped open the switch and bridged the contacts with solder.



This is a secure method, but I then realized it would make reprogramming difficult/impossible. On my 2nd version, I found you can run a 5/16-18 tap through the button guide tube in the case and use a homemade set screw to keep the stock switch closed mechanically.




Next, you need to find the +12v signal that is activated by the switch. This is available in the fuse panel under the H/L wash relay (R43) as shown in the photo.



NOTE/DISCLAIMER: This is the pin-out from my 1996 C2. I do not know if all 993's are the same. Do not proceed without first verifying your configuration with ohm meter, test lamp, etc.

All that’s needed is to connect the transmitter wires to the switched relay socket and the ground socket. In my first version, I simply added male spade lugs to the wires and Velcro’d the module atop adjacent short relays. All done and working perfectly!



But then, having apparently too much time on my hands – as well as an old Bosch fuel pump relay – I went to work on version 2. I sliced open and gutted the fuel relay, accessing the two needed contacts.



Out of caution, I removed two other lugs completely – the always-hot one and the one that is hot when the headlights are on. Also, for even more over-kill, I soldered in a 3 Amp fuse I had laying around.



Then it was just a matter of fabricating a mounting plate connecting the relay to the module - and then connecting the wires.



And plugging it in......



This was all “make it up as you go” design and a bit rough - but I’m very satisfied with the results. No more fumbling to get my remote out of the ash tray – both hands on the wheel at all times. And, as an added bonus, I’m no longer in danger of accidentally spritzing my clean windshield with unintended headlamp overspray – as has happened too often in the past!

Note: Be sure to keep your $90 H/L Wash relay in a safe place - in case you ever take up winter or mud night rallying - or if you live in MOT land and need functioning washers periodically.

Cheers,

Ron

Railmaster.

Ivan J

I'm surprised that the RF signal is strong enough with the transmitter located inside the closed frunk. Did you hook up an external antenna? How close to the garage do you have to be in order for this to work?

pp000830

Great Idea and DIY!

Why not let the stalk switch power the washers and the garage door opener? Just need to remember to turn off the headlights at night before opening the garage and if you need to clean your headlights on the open road you are probably nowhere near your garage so a unused radio transmission is of no consequence.

jrmdir

Good question. That's why I tried the quick install version first. Apparently the HL signal is strong enough - one of the transmitters works from about 50 feet out and the other from more than 100 feet. No external antenna.

Ron

gavonder

Forgive my ignorance, but I'm not familiar with Homelink. Do you not need to push a button to open the door? Is it automatic when you are close?

jrmdir

Another good question and a good idea - but that would take some intrusive wiring under the stock relay, I think. Would need to pick up the switched +12 for the HomeLink with the relay still in place. Not that hard to do perhaps - but I honestly don't know when I'd need to wash my headlamps while driving. However would be a good solution for those who do.

Thanks!

jrmdir

Yes, you need to push a button. Normally the unit is powered and the button initiates the open/close transmission. It's really a built-in, programmable substitute for the garage opener remote fob that comes with the openers. In order to make it a remote install, you reverse the operation. Force the button to be held down all the time - and toggle the operation by switching the power on and off. (Using the Headlamp washer switch in this instance)

This is how it looks in a donor visor:

AOW162435

Very slick!




Andreas

Foxman

Great write-up, and a very useful item - thanks for taking the time to post this!

jrmdir

Thanks everyone - it was a fun project. Once I got into it I kept thinking it had to be more complicated - but it all came together so nicely I wanted to share. I've learned so much from others here and it's great to be able to add to the knowledge base in return.

Now I'm thinking - what other uses could there be for this factory-installed "spare" switch circuit? - for those who don't need garage door openers.........

Ron

whitelightnin

First of all, thanks for posting this. Ingenious idea.

I decided to follow your directions and bought a sun visor homelink button off eBay but it has 4 wires coming out of it, not 2 like yours.

Each pair of wires has one solid black wire and one green wire with a yellow stripe. Do you have any idea why these two extra wires are there? They come out of either side of white plastic connector on one end of the homelink opposite of the button end.

jrmdir

Hi Whitelightnin:

Not sure, but since there are only two colors, Black and G/Y, it sounds as if your HomeLink may have been connected in line - with two wires "coming in" and "going out". One of mine was like that. Do the wires come into the back of the connector and continue out the other side? For reference, here is the one of mine that initially had "four" wires - in this case two black and two white. They originally continued on out of the connector towards the bottom right of the photo. I cut them off at the connector - as only one of each is needed to hook up to +12v and ground.

But then again, you might have something else entirely - Can you post or PM a photo of the wires and the connector?

whitelightnin

Yes, I found that the sets of wires are running in parallel, so it was just a matter of picking which pair to use. I have been able to connect to a 12V source and program the Homelink. Now I will get around to installing in the car. Thanks for the follow up. Again, great idea.

whitelightnin

It occurred to me that, according to the manual, the headlights must be on to operate the headlight washers. Does that mean that the Homrlink will only work if the headlights are on?