8.4AN Warning!!!!

[2013megacab]

Two days ago I was in Glacier NP on the Going to the Sun Road (highly recommended, BTW). My map had me off the road on one side, then the other, then the map rotated several 360 degree loops as I was driving straight. When I checked the signals it was locked onto multiple satellites. At that time the map position was correct.

Yesterday as I was leaving the positions and headings were all wrong. When I checked again I had no satellites. The system continued to try to route me, however. Today I still have no satellites. I am in West Yellowstone Montana and when I enable Nav it says I am east of Calgary, Alberta.

Apparently the system has a dead reckoning mode which it enters when it can't find satellites. The bad part is it doesn't work very well and the system doesn't tell you it has lost satellite lock..

This is a serious flaw and needs to be fixed.

Is there a fuse or setting that will kill the GPS and leave all Nav and satellite radio functions working? This navigation by paper maps and turn by turn directions printed from another system is a PITA!

Al

 

[GSykes]

This happened to me in Kansas a few years back in my 08, system went haywire. Showed me going west when I knew I was headed east, radio still worked. Your manual explains how to re calibrate the 8.4 NAV system, I did that then all was fine. Never had an issue again.

 

[Learjet]

gps jamming....military?

 

[2013megacab]

I thought that calibrated the compass. Did you check to see if you were receiving satellites at the time? I am not. I'll look it up and give it a try.

Thanks,

Al

 

[GSykes]

Al,
No I didn't, have no idea if we were receiving satellite signals or not. All I know is the screen didn't match our direction or location. It was working fine then all of a sudden nuts-o. Went through the process in the manual and all worked fine after that, never had another issue. Was still working fine when I sold the truck. Only thing I can say is try it and see if it works for you. Aren't electronic gremlins fun??? UGH...

 

[2013megacab]

Thanks, but....
There is no calibration process in my manual. I remember my 2006 F150 had one. There was a flux gate compass in the truck. It is similar to the compass app on iPad that you have to tilt and rotate the phone to calibrate it.

Apparently the compass heading on my truck is derived from the GPS. When I go to NAV/INFO/WHERE AM I/GPS it shows me bar graphs for the satellites and mine are all zero. I guess either the GPS part of my antenna has failed or the GPS module in the Nav 8.4 has failed, or a connector has come loose. I guess I'll let a dealer sort it out.

Al

 

[SnoKing]

Was Air Force 2 in the area with Pence? SnoKing

 

[2013megacab]

After several days, it got well. At first I thought maybe it couldn't get satellites due to the surrounding high mountains but next day we were in the clear and it still couldn't get satellites. I wonder if the new map update is only licensed for US and when I got within 4 miles of the Canadian border it turned off the GPS. So far, all is well.

Al

 

[Too Tall]

The 8.4 AN has a compass calibration procedure. It's basically; Get in a parking lot and drive around in a circle a couple of times. But check your manual it's in there.

 

[2013megacab]

The 8.4 AN has a compass calibration procedure. It's basically; Get in a parking lot and drive around in a circle a couple of times. But check your manual it's in there.

Thanks. I initially checked my manual but did not find a calibration procedure. I have several soft copy versions so I searched one and found:
"Compass Calibration
• This compass is self-calibrating, which eliminates the need to set the compass
manually. When the vehicle is new, the compass may appear erratic and the EVIC
will display “CAL” until the compass is calibrated.
• You may also calibrate the compass by completing one or more 360 degree turns
(in an area free from large metal or metallic objects) until the “CAL” message
displayed in the EVIC turns off. The compass will now function normally."

I take this to mean that I must be receiving a "CAL" message to activate the calibration function. I did not have such a message in my EVIC.

Several days after the failure the unit started receiving satellites again and has worked fine since then. I wouldn't think that the compass calibration would affect GPS reception. As soon as I got GPS reception, all the heading information on the screen was correct.

The larger issue is that the unit had, for whatever reason, lost all GPS satellites and did not report that fact to me via the screen, messages, or otherwise.

Al

 

[Learjet]

if it doesn't see GPS from being blocked by trees buildings, tunnels or jammed... it mostly likely uses Magnetic heading and speed info to continue to navigate...It's called DR (Dead Reckoning in the aviation world). So yes if the mag compass is off you could have problems if you have no GPS.

 

[2013megacab]

if it doesn't see GPS from being blocked by trees buildings, tunnels or jammed... it mostly likely uses Magnetic heading and speed info to continue to navigate...It's called DR (Dead Reckoning in the aviation world). So yes if the mag compass is off you could have problems if you have no GPS.

Yes, I understand all that. I even referred to dead reckoning (also in the boating world) in my first post. It is likely that the unit was not able to see satellites when the problem first occurred. But it didn't recover for several days even though I drove into clear line of sight to the satellites in less than an hour. Even if it somehow lost its "almanac" it had plenty of time to do a "cold start" since I was driving for most of the day every day until it finally recovered.

It continued to use the dead reckoning mode during the whole time without notifying me that it had lost satellites. Every other GPS unit I have had always identified that it could not see satellites. This one did not. The only reason I knew it had was that I poked around in the menus until I found the satellite status screen. The manual does say (see quote above) that it will put a message in the EVIC when it needs calibration. It didn't do that either.

I posted this to let others know that the unit will not let them know if it loses satellites and the dead reckoning mode can be VERY wrong. I'd rather it had said "sorry, can't display your position right now" instead of giving me a position that was off by several hundred miles without letting me know the possibility it was wrong.

Al

 

[SnoKing]

So I am on my way home from Habitat for Humanity build in Gold Bar, Wa. I punched in go home on the 8.4 nav and then stop in Monroe, Wa at Lowes to pickup some stuff. Come out and start to continue on home on a different route than the GPS wanted when I stopped. GPS is doing really strange things. I go to NAV, Information, My location, GPS and have zero satellites? Shut the truck off and restart it several times and still no sats.

I can not find anything in the owners or Uconnect Manual about resetting or calibrating it, other have driving clockwise circle at less than 5MPH which would be a compass cal process. Help.

 

[2013megacab]

So I am on my way home from Habitat for Humanity build in Gold Bar, Wa. I punch in go home on the 8.4 nav and then stop in Monroe, Wa at Lowes to pickup some stuff. Come out and start to continue on home on a different route than the GPS wanted when I stopped. GPS is doing really strange things. I go to NAV, Information, My location, GPS and have zero satellites? Shut the truck off and restart it several times and still no sats.

I can not find anything in the owners or Uconnect Manual. Help.

Sounds like exactly what happened to me. No satellites, but no warning, just following crazy headings. I was going to take my truck in but after several days and several starts, it just got well. You could try disconnecting the battery to re-boot the Nav but it also reboots everything else.

Al

 

[SnoKing]

Sounds like exactly what happened to me. No satellites, but no warning, just following crazy headings. I was going to take my truck in but after several days and several starts, it just got well. You could try disconnecting the battery to re-boot the Nav but it also reboots everything else.

Al

While you were posting this I was out in the truck trying this.

"Try rebooting Uconnect; have the ignition in the run position with out starting, press the center of both the round MUTE and the ENTER/BROWSE for 5 seconds then wait a few seconds and it should start reboot. Hope that helps"

Found it at:
https://jeepcherokeeclub.com/65-ele...g/108170-8-4a-navigation-lost-gps-signal.html

AND it fixed it!!!

 

[Wayne M.]

I have 8.4 in the R/T. I might agree with satellites being a problem, especially if the same satellites are used for the Sat radio. That’s been dropping the signal quite a lot lately.

 

[SnoKing]

I have 8.4 in the R/T. I might agree with satellites being a problem, especially if the same satellites are used for the Sat radio. That’s been dropping the signal quite a lot lately.

Different sats and receiver, and most likely antenna. Trees, hills, mountains(South of your location), rain and other weather conditions really effect XM/Sirrus reception.

 

[SnoKing]

The only thing that I think might have caused this, is that I opened the drivers door and reach in and touch the start button to activate assy mode to open the rear sliding window to put in a 12' 2x4. I left the door open for several minutes while I was sliding the 2x in and strapping it down just pass the tailgate. The truck was beeping at me all this time while the door was one and the fob was outside the truck. Maybe it got p i s s e d off.

 

[2013megacab]

While you were posting this I was out in the truck trying this.

"Try rebooting Uconnect; have the ignition in the run position with out starting, press the center of both the round MUTE and the ENTER/BROWSE for 5 seconds then wait a few seconds and it should start reboot. Hope that helps"

Found it at:
https://jeepcherokeeclub.com/65-ele...g/108170-8-4a-navigation-lost-gps-signal.html

AND it fixed it!!!

Nice! Now if I can just remember it if it happens again.

Al

 

[SnoKing]

Nice! Now if I can just remember it if it happens again.

Al

Well I am glad, as if I took it to the dealer for a MaxCare Warranty repair they would have wanted to do the drag link recall, and I am holding out with my Blue Loclite band aid waiting for a replacement part vs the welding. Snoking