2009 Edge Nav off by 1/4 mile

[JohnCT]

2009 Edge Limited.  The NAV works but it always lags about 1/4 mile behind regardless of direction.  In the diagnostic menu, it shows anywhere between 2 and 5 satellites depending on conditions, but it's always behind.  Needless to say it's tough or impossible to use.

 

I went into the phone section and did a reset and that didn't help.  I don't see any method of resetting the NAV or calibrating it.  This is a car I gave to my sister a few years ago, and it worked properly when I last had it.  Is it just too old to work?   BTW, I just picked up another antenna on Amazon, and it acts the same way.  Thanks.

 

John

[ebank]

2-5 satellites seems to me like a very low number, where is the vehicle located?

With an older unit the gps almanac has to be updated for the unit to track the satellites orbits.
The almanac is transmitted every 12.5 minutes, so after a hard reset like you did, the cold gps start may take some time.

If you are in a city with tall buildings you may be having trouble getting the almanac as well.

 

https://en.wikipedia.org/wiki/Time_to_first_fix#:~:text=Almanac data can be received,for up to 180 days.

[JohnCT]

56 minutes ago, ebank said:

2-5 satellites seems to me like a very low number, where is the vehicle located?

With an older unit the gps almanac has to be updated for the unit to track the satellites orbits.
The almanac is transmitted every 12.5 minutes, so after a hard reset like you did, the cold gps start may take some time.

If you are in a city with tall buildings you may be having trouble getting the almanac as well.

 

https://en.wikipedia.org/wiki/Time_to_first_fix#:~:text=Almanac data can be received,for up to 180 days.

 

In Connecticut, which tends to be hilly with a lot of tall trees.  

 

Here's some more info that I didn't think to mention: this car had a bad tone ring - so to keep the ABS from chattering the brakes on dry pavement, I pulled the ABS fuse which disabled the AWD, ABS, traction, and stability until I had the chance to install the new axle.  Disabling the ABS also eliminated the NAV from dead reckoning using the car's speed sensors (like when in a tunnel or in a tall stand of trees), so the radio announced a Nav error.   Once I installed the new axle and restored the ABS,  the GPS still refused to dead reckon even after a couple days of usage.  Resetting the phone settings suddenly allowed the dead reckoning to work and the NAV is now functional again, except of course for the 1/4 error.  I'll drive it a few more days before giving it back to my sister and see if the NAV sorts itself out.

 

Thanks.

 

John

[WWWPerfA_ZN0W]

any changes in tire/wheel sizes from oem? if the odo/speedo is off, typically the nav will be too.

 

battery might be involved if it is weak and not providing proper voltage to the various modules in the vehicle but that is a very long shot.

[JohnCT]

33 minutes ago, WWWPerfA_ZN0W said:

any changes in tire/wheel sizes from oem? if the odo/speedo is off, typically the nav will be too.

 

battery might be involved if it is weak and not providing proper voltage to the various modules in the vehicle but that is a very long shot.

 

No, running stock wheels and tires.  Battery about two years old and tests perfect on electronic analyzer.  Thanks for the reply.

 

John

[enigma-2]

Car following but 1/4 mile off after power disconnect. 

 

First try a radio reset. Disconnect all fuses powering radio (3-sync, 28-radio, 39-radio, 41-delay). Or pull cable from battery and wait a few minutes. 

 

If radio still doesn't reset, try master reset. (Thru radio menu).

 

One or the other shoud force nav to reset inner time and correct (think inner clock is off, interpreting satellite info wrong). If this fixes nav error and it goes bad again, possibly a apim going bad.

 

 

Edited February 24, 2022 by enigma-2

[JohnCT]

The NAV straightened itself out.  It probably had to figure itself out after I reset it a few days ago.  It's now on track and usable.

 

One thing I noticed is that the "no gps" warning square pops up on and off on the display while driving today.  This was my wife's car before we gave it to my sister and she doesn't remember the no gps indicator, but then, she might not have noticed it even if it did pop up.  Is this abnormal?

 

This has a new antenna and it acts like the other antenna I changed a few years ago. I also tried reconnecting the original antenna still mounted under the dash and it doesn't work at all.  So the original antenna was bad and I've tried two Chinese aftermarket antennas that work - kind of.  I wonder if the marginal reception is because of the cheap antennas.  At least it works so I'm not going to worry about it.

 

Thanks for the help everyone.

 

John