Navigation / compass is off
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Junior Member
Joined: Sep 2024
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From: Western NY
2017 GLS450
Navigation / compass is off
So my 2017 GLS450 shows the vehicle location about 150 miles west of where it should be and the compass is roughly 180deg off. What's the diagnostic procedure on this?
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Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
Most likely cause is that your GPS antenna died or the wiring to it is faulty. I forgot exactly where this is in the old COMAND system, but somewhere under the position details in the navigation area you can see the number of satellites that it has a fix on. It'll likely say zero in your car. You need a fix on at least 3 satellites and 4 for altitude. If it doesn't have a fix on enough satellites, then the navigation relies on other sensors in the car such as wheel speed, steering angle etc. to approximate your current position based on how far and in what directions you've been traveling since the last known GPS fix. Over time this algorithm drifts off, unless it gets a periodic correction from a satellite fix, so the longer it goes on without receiving any position data from the satellites, the farther your current position drifts off from the actual position. There's nothing to reset. You gonna have to get your GPS reception fixed. Once you get a good fix on enough satellites again, it will correct your position and direction of travel.
Last edited by superswiss; Aug 26, 2025 at 01:42 PM.
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From: San Francisco Bay Area
2019 C63CS
Yes, the shark fin is the GPS antenna. MB got rid of the shark fin in later models for a cleaner look and integrated it into the driver side mirror if I remember correctly. You may have noticed that newer MBs don't have any ugly antennas sticking up as opposed to many of the competitors still having the ugly shark fin on the roof. The problem with the shark fin is also that the seal can start leaking and water gets into it. Besides the antenna going bust then you also have a leak in the roof, which is no fun. Some people have also caught their garage door with it and partly ripped it out. All in all, the shark fin was a bad and lazy idea.
Last edited by superswiss; Aug 26, 2025 at 07:58 PM.
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Out Of Control!!
Joined: Nov 2018
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From: San Francisco Bay Area
2019 C63CS
That would do it. Sounds like your antenna is not completely busted, but it has failed to the point where it can't track multiple satellites anymore. Other possibilities are interference or natural obstructions where you live that prevent it from seeing more satellites.
Thread Starter
Junior Member
Joined: Sep 2024
Posts: 17
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From: Western NY
2017 GLS450
That would do it. Sounds like your antenna is not completely busted, but it has failed to the point where it can't track multiple satellites anymore. Other possibilities are interference or natural obstructions where you live that prevent it from seeing more satellites.
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2019 C63CS
I haven't replaced one, but I've come across others who had to do it on non-Mercedes models and it involves taking off the entire headliner so you can get to it. Once the headliner is off, they are relatively easy to replace. They are screwed down from below.
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From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
Hopefully the attachments will either help or convince you to have someone else do it. You apparently do not have to remove the headliner.
That said, the antenna doesn't know if it is receiving five satellites or just one. Have you tried a different location?
That said, the antenna doesn't know if it is receiving five satellites or just one. Have you tried a different location?
Last edited by John CC; Aug 29, 2025 at 03:44 PM.
Thread Starter
Junior Member
Joined: Sep 2024
Posts: 17
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From: Western NY
2017 GLS450
John, appreciate the shop docs. Would you mind restating your last sentence above, I don't quite follow. Appreciate the reply.
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2019 C63CS
Last edited by superswiss; Sep 2, 2025 at 12:43 PM.
MBWorld Fanatic!
Joined: Jun 2021
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From: New Hampsha
'17 GLS450, '14 GLK250, Grandpa's Roadster
I'm not saying you're wrong, but I doubt that is what is happening here. For one thing, the antenna itself is not exposed to the elements, Secondly, if it was a band related issue, I would expect inconsistent results whereas he's reporting consistence, which to me points to something farther down the logic line.
That said, in my experience in the aviation industry, I've never encountered a situation where a GPS antenna that had to be replaced for poor performance. They either worked or they didn't. (Usually they were physically damaged.)
Then again, I could be wrong...
That said, in my experience in the aviation industry, I've never encountered a situation where a GPS antenna that had to be replaced for poor performance. They either worked or they didn't. (Usually they were physically damaged.)
Then again, I could be wrong...
Last edited by John CC; Sep 2, 2025 at 01:29 PM.
Out Of Control!!
Joined: Nov 2018
Posts: 11,311
Likes: 5,273
From: San Francisco Bay Area
2019 C63CS
I'm not saying you're wrong, but I doubt that is what is happening here. For one thing, the antenna itself is not exposed to the elements, Secondly, if it was a band related issue, I would expect inconsistent results whereas he's reporting consistence, which to me points to something farther down the logic line.
That said, in my experience in the aviation industry, I've never encountered a situation where a GPS antenna that had to be replaced for poor performance. They either worked or they didn't. (Usually they were physically damaged.)
Then again, I could be wrong...
That said, in my experience in the aviation industry, I've never encountered a situation where a GPS antenna that had to be replaced for poor performance. They either worked or they didn't. (Usually they were physically damaged.)
Then again, I could be wrong...
