Transcript for Woman loses internet service, runs out of gas while alone near Grand Canyon: Part 2
Reporter: It is Sunday, March 12th, day two of amber Vanhecke's great american road trip. And her fernweh, that favorite term of hers for wanderlust, is in high gear. Where did you go next? To the grand canyon, actually. Reporter: The grand canyon is on most Americans' bucket lists. And now, amber is fearlessly checking it off hers. And I assured my mom, "She's okay." I have an undying, like, faith and trust in my sister that can take care of herself. Because my sister's strong. It didn't occur to me about getting lost in the desert. Because I have really decent navigation skills. Reporter: Along with those skills, she's also got a navigation app, the always reliable Google maps to be precise. She types in the name of her next destination. The havasu falls trailhead, a remote spot in the grand canyon with aqua blue plunge pools so popular, it requires a reservation. That's the trailhead? Yes. Reporter: It's in the middle of nothing. Yes. Reporter: All right, let's go. It says 63 miles. And you only had 90 max on your tank. This week, we return with amber to this fateful spot. The place where, directed by her smartphone, amber turned off highway 64 and onto this dirt road. Google said to go on a road that I didn't see. And I went against my better instinct. I trusted Google maps, which I shouldn't have. Reporter: Let's face it. We're all too dependent on our devices to get us places. And amber's not the first to discover that can nearly get you killed. Just ask Donna cooper. Back in 2010, she, too, trusted her gps and followed it blindly during a trip through death valley. Nearly finding out for herself how one of the hottest places on Earth got its name. It just kept saying, you know, go this distance and make a turn, make a u-turn. There's nothing there. We were out of gas. We were out of road. We were out of everything. Reporter: "20/20's" Jay Schadler saw how navigational technology can sometimes be dangerously outdated. Turn right on golden canyon road. Reporter: I don't see a road. What we have here is a canyon wall. Oh, definitely. The road used to go at least a mile in here, but that washed out in 1976 in a flash flood, so, this road has not existed for 35 years. Reporter: And a similar gps shortcoming is about to threaten amber's life, as well. After she makes that fateful turn off highway 64. Turn right. Turn right. Reporter: So, we're making a right. It's already a dirt road. And so you thought that this would be a blacktop road? I had thought so. And then when I got on it and it -- it seemed like a really -- Reporter: Wow. -- Well taken-care-of gravel road. Reporter: But it is a gravel road. Yes. Continue for 14 miles. Reporter: So, we're barely a mile off the road and we're driving in empty space -- check that out. Even if you had a compass and a map, look around. You don't have known points. You don't have mountain peak, you can't do that out here. You don't have anything. It's rough. Reporter: And so with night now falling, amber drives for another hour and a half. Farther and farther into the middle of nowhere, which is actually right in the middle of Gary Wilson's 1,200-mile square ranch. One of the biggest in the west. It's happened to several other people, trying to get across this ranch. Google Earth tells you that you can, but this ranch is actually closed. I couldn't really see very well. Just whatever my headlights lit up. Reporter: And what her headlights lit up next spelt And then, about when I came to the fence and I was like, oh, there wasn't a road here. That's when I was like, this is Reporter: What goes your through your mind when you hit supposed to be? That's when I tried going into the gps app, and telling it to take me back, help me take me back, and it was like, sorry, you have no internet service, and my heart just panicked. do you start calling 911? I called 911 as soon as I realized I didn't have the road anymore. Reporter: As amber frantically dials 911, for a fleeting moment, a connection. state. When they said, "What is the nature of your emergency," I just let out a sob and I said, And I heard it drop. And I just -- Reporter: It's still tough for amber to recall. As her panic swells, her most precious resource dwindles. I was trying to watch my gas. like, petting my car, like, come on, baby, just a little further, we got to find a road. Reporter: Is that Orange light blinking yet? Oh, it had been blinking. So, I was like, okay, I'm going to stop for the night, because I'm just wasting more gas and I'm digging into my reserve more and more as I drive on and panic. Reporter: Amber parks along the first manmade structure she finds, hoping this sign of civilization might mean possible rescue. And hoped for the best. Got in the back. sleep. mind races to the loved ones who have no idea where she is and who may never see her again. Who was the first person you started to think about? My dad. thoughts of, like, maybe I should leave a message in case video. Reporter: A video diary in total darkness. Her face not visible at all. I've never really been, like, In case I don't, like, get found, I have a lot of things to say. Reporter: It was basically a will and testament. I thought that it had the potential to be the beginning of I love my family, mom, dad, Kayleigh. I just want to go home. I don't even want to do this trip anymore. Reporter: When we come back,
This transcript has been automatically generated and may not be 100% accurate.