Prairiedawg

Thank you for the detailed instructions.

sandwedge

Impressive amount of solutions and suggestions here. I know this won't help the OP and I'm sorry about that but I've read enough horror stories like this where I've programmed my brain to a simple solution to avoid what seems to be happening on a regular basis: Whenever I do anything with the battery....disconnect for a 2 or 3 week trip out of town, replacing the battery or anything involving disconnecting the battery I ALWAYS put an old thick towel over the locking mechanism of the frunk where you can't close/lock it no matter how hard you try.

I've had the door sill switch fail twice between the three 997's I've been through but the FOB on the key always worked as a backup. So as long as you have battery power you'll get into the frunk. Never heard of a case where the door sill switch and the key function both failed with a good battery.

Petza914

I do the same thing.

CAVU

Shade tree mechanic'n time.

I did some exploring in the wiring diagrams.

Basics:
- Frunk "Emergency Opening". The Porsche manuals uses the term to describe the Emergency entrapment opening from inside the frunk and the subject at hand. So if you go rooting around in the electrical diagrams, just be aware.
- Whenever the "Pin", referred to as "Positive" Terminal (red) in the owner's manual, in the fuse box is pulled outward, no switches are tripped. It is a dumb unpowered connection point.
- There are conductors on both sides of the Pin. I have not tested this thought yet, but it is only necessary to make good contact with one of those conductors. Depending on the jumper cable positive clamp design, I wonder if it is possible that good contact might not be made...something to consider. Something for folks to consider is the Pin conductors are ONLY ON THE SIDE. So the clamps must clamp from the side.
- The Front Control Module appears to be where everything happens up front including normal and emergency opening of the frunk via the Pin.
- Fuse 3 on Row C, 10 amps, is connected to the Front Control Unit.

Logic path:
- So the + and - cables have been connected per the manual.
- Once the Pin has + power (did the ground clamp spark a little bit at the door? if yes, you have power. Just a thought).
- This is where it gets interesting. Two positive lines leave the Pin and go to a relay. One + lead activates the relay, removing power from a number of "normally" connected systems and simultaneously makes a new connection that sends power to a limited number of systems, one of which is the Front Control Unit.
- Now it is time to hold down the key fob open frunk button for at least 2 seconds.

If it is not working, time for fault checking:
- remove the cables
- check Fuse 3 Row C for continuity
- check the health of the 12v DC source
- after reconnecting the power leads, use a volt meter and probe the Pin conductor plate. it should show 12v.
- Try the key fob again.

Just a few thoughts from the cheap seats. Inputs are most welcome.

Prairiedawg

Excellent sleuthing. That makes sense, have a relay to power the control module while removing any other load on the jump battery. That explains why the door switch doesn't work, it may go through another module and/or canbus system. Unfortunately it can have 2 failure modes in the relay or the control module. The relay is unlikely as it is never used but in this rare circumstance. The control module could with low voltage issues due to the dead battery but if that happens AND you're locked out of the frunk, you have really rotten luck. I think the wire from the latch to the marker light is a prudent step to take.

Floyd540

CAVU, thanks for the info and follow up to my question about the actual wiring for this emergency operation. I knew something had to be tricky about it but I don' have the wiring diagrams. As with any complete answer, more questions are raised. What is the "secret " relay and where is it and does it do anything else except the emergency frunk procedure?
This also proves that following the Porsche instructions exactly are the only way to get this to work. It really is an elegant and pretty much fool-proof method to deal with the problem (electrically speaking that is). The pull out contactor in the fuse box does seem a little odd with the two narrow contact patches on each side. Even odder (odder?) is that they are slightly recessed. A battery jumper clamp opens up wide enough but the face width of the jaw may be too wide to make contact. However if you have other electrical spring clamps in your collection, you will find one that fits the contactor perfectly. I am guessing that the German Porsche engineers assume that we all have the proper and correct clamps in our electrical bench. I have one but that is just based on luck. Anyway, you just need to somehow hook the +12 V to one or both of the contact patches and you are good to go!
I may be the original shade tree guy. Originally from Kentucky and two of my cars still have cranks to start them. An oak tree and a chain fall and we can fix anything.

CAVU

A caution to all readers. There are only a few facts that I have presented. The rest is supposition. Still fun trying to figure it out. It is also enlightening. The newer the car, the more sensors, servos, relays, modules (computers) and switches there are.

Per Sheet 33 Construction Components, US drivers, left footwell on "left Relay Support 1" I count at least 9 relays at that site.

I think the main culprit to successfully opening the frunk using the emergency method is the Pin's design/structure. A better design would have been 100% conductor on all four sides. I think the second culprit is making ground. That ground point identified in the manual is not very big. I would use the door catch.

I think I will experiment this weekend and see what I experience. I will be leaving the hood open and simply false close the latch.

CAVU

The relay is only there to support emergency opening of the frunk using the Pin.

Just some random thoughts/suppositions:
- It would be highly unlikely that the relay has failed because the relay coil is never activated unless powered through the Pin. A completely opposite situation to a fuel pump relay.
- Front control unit failure due to dropping voltage from a discharging battery is unlikely. I believe automotive control units have some level of protection against that possibility.
- I suspect that with a quiet environment, you can hear the relay "click" when energized and deenergized via the Pin given its proximity to the Pin/fuse-box. If the the car was locked with the remote, the Alarm will go off when the Pin is energized. No doubt on that one.

ZuffenZeus

Lots of help offered to you. Whatever came of your ordeal?

tinroof

Hi Wayne, I followed your instructions and connected a 4-5 ft. length of parachute cord to one of the hooks at the bottom of the frunk lock assembly. I ran the cord to the right side running light. The hardest part was getting the running light removed. I wrapped the free end of the cord with duct tape and attached it to the metal recess below where the running light sits. I hope I never need it but I'm very glad to have this emergency cord in place.

Ironically I locked myself out of my frunk less than a week after I bought my 911 (in 2019) while attempting to run an additional wire from the frunk lock to the driver's side running light. I didn't test it sufficiently before I closed the lid, and to my horror, my "fix" interfered with the normal operation of the frunk lock so there was no way to get in. After several days of trying different strategies, I finally gained entrance by poking a wire grabber into the lock area and fishing around until the wire on the solenoid dropped back into place. Since then I've been afraid to try again but I got up my courage and installed this, which is a much better and easier way to go. Thanks for your clear instructions and photos!

BTW, people who haven't removed the frunk lock assembly should be aware that you loosen the two bolts from the inside of the frunk (using a ratchet and 10mm socket) after loosening the frunk liner on the inside of the frunk. I initially wrongly thought that I should loosen what appeared to be square nuts on the lock side of the lock assembly but then realized that those square things are not nuts but rather are threading points into which the lock bolts attach.

Wayne Smith

Once I looked closer at this it became obvious and so simple I kicked myself for not doing it years ago. My hurdle was giving up on trying to figure out what the Porsche engineers had in mind. At least on the 997.2 cars the design was ridiculous. I spent many wasted hours on this before yanking the latch.

Latch ... Mark around the washers with a Sharpie before removing the bolts so you can put it back on with proper adjustment.

Right front side light ... Push back from the front edge and it pops right off.

And thanks again to Petza for suggesting the side light as a location to store the cable. That is a lot easier than removing the wheel and fender liners.

This won't help the OP get his frunk open, but it will avoid a second disaster.

tinroof

With your routing to the right side light my emergency cord has plenty of purchase to open the latch.

I did notice that my frunk lid is closing a little deeper now, and I guess that is because I lined the lock up a little lower when I reinstalled it. (I didn't mark around the washers with a Sharpie to guide me back to the perfect location for the lock on reinstall.) I will just have to readjust it a bit so that the frunk lid sits a bit higher after it latches. It's only slightly off at present.

Thanks again for your guidance, and to Petza too.

whacko77uk

A few months ago I disconnected the battery and closed the frunk. I called out Porsche Roadside Assistance who used a jump pack on the fuse to pop the lid. It only works by keeping the key fob button pressed for a few seconds. I don’t know why but it only works this way and not using the flick switch on the door sill.

Mine is a 997.2.

8x57IRS

Excellent explained in post #34. Voltage is withdrawn from other systems in favor of the emergency opening.

Prairiedawg

So, is this guy still standing there looking at his locked frunk?