I recently installed a Clarion NZ501 in my car. The only problem I am having is when I open the navigation, it says Auto Detecting GPS and never gets past that.
Can anybody help me with this?

Using the search function, I found

post66658.html#p66658
post83093.html#p83093

I read both of those, and they didn't help.

Anybody have any other thoughts?

So you are saying and are 100% the settings in sys.txt are correct?
Then the GPS chip may be broken.

No, I am not sure the settings are correct. That is how I ended up here in the first place. I was trying to find the correct settings for this model, or confirm the settings are correct.
I bought this unit factory refurbished a few weeks ago. Everything else works great. I don't know for certain it is the original SD card (since it is a refurb, I assume it is). I downloaded and installed the latest maps and updates from Naviextras to make sure everything was up to date. I have even tried a different antenna. Nothing is working.

I have also tried changing the baud and port settings in the sys.txt file.

Here are the original settings in sys.txt:

[device]
type="CLARION_NX501"
sdcard_name="SD"

[folders]
sdcardpath="\SD"
data="/BACKUP/save"

[gps]
port=1
baud=9600

[project]
name="clarion_skypine"

[loading]
background_startup=1

[smart_routes]
enabled=0

[rds]
icons=0

[tmc]
init_on_startup=0

try

[gps]
port=1
baud=38400

Or comment out the lines of port and baud.
Also delete the save folder, since there are most certain the wrong values in it.

Thank you...I will try those values
I have read about deleting the save folder, but I can't locate it anywhere.

May not be relevant to the GPS problem, but...

[folders]
sdcardpath="\SD"
data="/BACKUP/save"

...in the data line you are using Unix style file paths, rather than dos style.

It should be...

data="\BACKUP\save"