GPS lost?

[propman07]

Hi- Recently, my Z110BT (upgraded to the Z120BT) has been having trouble with showing my current location. Sometimes, it gets the position on the road correct, sometimes it appears lost. I also noticed that in the connection status screen, the unit no longer shows any speed pulses from the VSS. Any thoughts on troubleshooting advice? Thanks.

[RonS]

Hi- Recently, my Z110BT (upgraded to the Z120BT) has been having trouble with showing my current location. Sometimes, it gets the position on the road correct, sometimes it appears lost. I also noticed that in the connection status screen, the unit no longer shows any speed pulses from the VSS. Any thoughts on troubleshooting advice? Thanks.

 

 

VSS is more for dead-reckoning. If your GPS is good, it isn't necessary (but if it worked before and now doesn't, then you likely have a wiring problem). How is your GPS signal strength? Go to Settings/Navi Settings/Connection Status. The line GPS Antenna should say "OK", if the signal is good. The number of bars indicate the strength. The numbers to the right of the orange icon indicates how many satelites are being used to calculate your position - should be > 2. The number to the right of the yellow icon indicate satellites detected but which cannot be used.

 

If reception is poor, 1st check/change the location of the GPS antenna.

 

Odd that GPS and VSS would go bad at the same time. Any possibility the wires behind the unit got disturbed? Maybe some loose connections. Also check for chaffed/frayed wires.

[propman07]

RonS- Thanks for the reply. I installed the unit over a year ago, and it is just now starting to act up. I checked, and I have more than two sats locked (it got as high as 11). Signal strength was good. I noticed that the VSS pulse count was working for a few minutes as I started to drive, then it stopped. I'm going to start looking at a loose wire. Hopefully, that will be the cause. Thanks again.

[RonS]

RonS- Thanks for the reply. I installed the unit over a year ago, and it is just now starting to act up. I checked, and I have more than two sats locked (it got as high as 11). Signal strength was good. I noticed that the VSS pulse count was working for a few minutes as I started to drive, then it stopped. I'm going to start looking at a loose wire. Hopefully, that will be the cause. Thanks again.

 

 

Maybe try a reset before tearing things apart. There is a way to reset some of the sensors. In NAVI Settings/3D Calibration. Reset everything then drive around for a few miles. If that doesn't work, try a factory reset. You'll loose your settings, but that isn't so bad.

[propman07]

RonS- I pulled the unit yesterday in an attempt to locate the loose connection on the VSS wire. No dice. I checked where I'm taping into the vehicle harness, as well as the connections to the unit itself. Everything looks okay. I put everything back together, and reset all of the sensors. No speed pulse indication, but the mapping seems to be working a little better. I did notice that when driving to a destination, the unit would lock up when it displayed the close up instructions for a turn at a corner. The nav pointer would appear on the screen, then begin to rotate around...kind of crazy. I think that I am going to try to restore factory settings to see if that does anything. After that, about the only other thing that I can think of trying is to verify voltage off of the VSS lead.

[RonS]

After that, about the only other thing that I can think of trying is to verify voltage off of the VSS lead.

 

Just to let you know, the VSS is a pulse. It is different from vehicle to vehicle, and I doubt you will have a sensitive enough voltmeter to trigger the current reading. I couldn't quickly find any standards (like IEEE) for VSS, but I'd bet there is one - defacto at least. I don't know what marks the pulse (polarity/voltage threshold...). BTW, are you sure it ever worked?

 

The turning/rotation issue could be caused by other things. There is an internal gyro/sensor that only works correctly if the HU is mounted at an angle less than 30 degrees from horizontal and within 5 degrees left/right. I doubt that is your problem - but just wanted you to be aware. Seems like it would never of worked if that was the problem.

 

After a reset, drive for a few miles, then go to the 3D calibration screen under Navi Settings (while parked). Is the Speed Pulse value 0? If so, either the unit is bad or the wiring/connection isn't good. Now, while you are on this screen, drive around (safely) and make a few turns. (See pg 149 in the Z120 manual). You should see changes in the spee and rotation as you move. Also, what does it say next to "Learning Status".

[propman07]

RonS-

 

Thanks for the info on the VSS. I know that it did work, because when I reset it the other day, I saw the pulse count start to increase, and the signal bars started to change. The HU is mounted within the 30 deg / 5 deg parameters. I bought the HU in July of 2009, and it has worked flawlessly up until about a month ago when it started to have problems.

 

I will try to drive around to see if the speed pulse value changes. It is currently at 0. I will also see what it says regarding learning status. If I remember correctly, it currently says simple hybrid.

 

Thanks for the troubleshooting ideas. I'll post results later.

 

Just to let you know, the VSS is a pulse. It is different from vehicle to vehicle, and I doubt you will have a sensitive enough voltmeter to trigger the current reading. I couldn't quickly find any standards (like IEEE) for VSS, but I'd bet there is one - defacto at least. I don't know what marks the pulse (polarity/voltage threshold...). BTW, are you sure it ever worked?

 

The turning/rotation issue could be caused by other things. There is an internal gyro/sensor that only works correctly if the HU is mounted at an angle less than 30 degrees from horizontal and within 5 degrees left/right. I doubt that is your problem - but just wanted you to be aware. Seems like it would never of worked if that was the problem.

 

After a reset, drive for a few miles, then go to the 3D calibration screen under Navi Settings (while parked). Is the Speed Pulse value 0? If so, either the unit is bad or the wiring/connection isn't good. Now, while you are on this screen, drive around (safely) and make a few turns. (See pg 149 in the Z120 manual). You should see changes in the spee and rotation as you move. Also, what does it say next to "Learning Status".

[propman07]

Update: Speed pulse still at 0 after a reset to factory settings performed. Learning status is simple hybrid. I checked the wiring for the VSS, and as near as I can tell, it appears okay. I also checked the connections to the HU, and they look okay as well. I'm guessing that something is wrong with the HU internally. Now, I need to decide if I want to pull the unit and see about sending it in for service, or bite the bullet and purchase a new one.

[RonS]

Update: Speed pulse still at 0 after a reset to factory settings performed. Learning status is simple hybrid. I checked the wiring for the VSS, and as near as I can tell, it appears okay. I also checked the connections to the HU, and they look okay as well. I'm guessing that something is wrong with the HU internally. Now, I need to decide if I want to pull the unit and see about sending it in for service, or bite the bullet and purchase a new one.

 

 

VSS is really not necessary - it just improves dead reckoning. Is your position on the NAV plot still messed-up? Still doing donuts? That is the biggest issue. Does the 3D calibration screen turn when your vehicle turns? If that stuff isn't working then yes, it's time for service. It sounded like even when the GPS knew where your location was, it didn't know what direction your vehicle was heading (or orientated). That sounds like internal sensors. So VSS might be part of a whole bunch of things that aren't working.