2006 Xt5 Satnav/gps Failure

[Zathras]

Hello!

In the last couple of months I've developed issues with the Satnav, specifically the GPS tracking of my position.

There are two problems, firstly the calibration is off and setting it manually doesn't resolve the issue. It is always out by approximately the same amount, offset by about 50 metres at a guess. This is more than enough for it to keep snapping to adjacent roads while driving, so it will continuously re-reoute or think I'm driving in the field next to the road. Sometimes it is close enough to track me on the correct road but doesn't seem to last.

The second new feature is that after a while it seems to give up and freeze my location altogether, this can stay the case for a couple of journeys before finally starting to track the position again. I'm not sure if this is the GPS genuinely failing to track my location or if the software has just given up by semi-crashing from all the re-routing or continuous snapping about to random roads.

It all started not long after having new tyres fitted and the speed is slightly more misrepresented than before, so my obvious thinking was calibration. But any new manual calibration just doesn't seem to hold; I calibrate for my location and pull away, it immediately snaps back to the offset position again.

Sometimes the tracking is spot on but this appears to be a worsening situation with it now more often failing than working.

I had it in for the front pads last week and the Toyota garage had a quick look into it, found there were software updates to the unit and started to apply them. They did 2 of 4 on the day and it is going back in next week for the remaining ones, but they don't hold up much hope in it fixing it. They will also be fixing a water leak into the passenger area (a known 2006 model issue), I do hope this water hasn't reached the head unit causing damage.

Not sure what the next move should be, I would hope that a replacement unit isn't required for just a GPS failure and I would almost certainly replace with something else other than a Toyota standard unit if that were the case. (I had been eyeing up the Kenwood DNX7240BT to give me iPhone connectivity/dvd/improved audio which my local specialist will fit do for less than Toyota standard replacement, but that's another story)

Any thoughts on this would be appreciated.

[Joylove]

Do you have an ABS light on? It could be one of the wheel speed sensors is damaged, breaking the dead reckoning on the GPS.

[shcm]

I don't understand the dealer doing "2 out of 4" software updates, whatever that means. As I understand it, for that unit, any software updates should be on the latest map dvd. There is not just map data on there. The unit boots from the DVD when first connected to a power supply (car battery) and turned on. Using the latest DVD I believe would mean having the latest software!

It's possible there's some additional firmware that can be upgraded, however I'm skeptical as I only ever remember seeing provision for a memory backup tool in the diagnostic menus. Ask the dealer for a detailed explanation of what he's done/doing.

Anyway, talking of diagnostic menus, the unit has one and I would have thought the dealer would have used it.

To get it into diagnostic mode, select the display screen with the display button, then on the left hand side of the screen, tap top (first) and bottom with your finger three times (6 taps in all). If it doesn't work, just keep taping top and bottom until the display changes to a menu on a white background. The areas in which to tap are shown with the dash boxes in the pic below:

Once you get into diag mode, just tap the various black menu items to get access to various parts of the system. You probably need to check GPS reception and wheelspeed input. Have a look around the menus. I've probably got picture somewhere to show you what/how to access various diag displays, but afraid I'm a bit busy to find them at the moment and is is usually self evident anyway.

Find the GPS satellite reception screen. It should show time in GMT, your position and a whole heap of satellite numbers that should be in view overhead. If I remember correctly any sat not being received will have a "P" next to it. Otherwise there is a number representing receive strength. Get the vehicle out into a reasonably clear area (away from buildings) and check you are receiving at least 4 sats. Usually it will be a lot more.

There is also a screen that shows vehicle speed and also things like yaw rate. Get this one up and go for a drive and check that it shows sensible speed values. This will confirm whether the wheelspeed I/O is working correctly. (Actually, I'm trying to remember whether actual vehicle speed is displayed or whether it is just wheelspeed pulse frequency input, so forgive me if it is not actual mph/kph that is displayed).

It does sound like wheelspeed is not being input properly to the unit. But having a guess off the top of my head, it could also be things like the GPS antenna (mounted under the dash in the centre), GPS antenna lead, GPS antenna plug.

To get out of diag mode, just power off, or press and hold the display button.

The dealer really should know about this diag function anyway and have check everything out. Perhaps ask him to show you ;).

My later unit is very often not spot on and junctions (if you're zoom in to max), but it's good enough as far as I'm concerned.

Good Luck!

[Zathras]

Fantastic, thank you.

I had been in the diag menu previously regarding BT/MIC issues and completely forgot there was a GPS reception screen.

So now for the results...

Sitting outside the house where I would normally have a perfect position shows what appears to be 1 satellite locked on with a low LVL (5).

On a quick drive around the area it showed at most showed 3 satellites locked, all with low LVL (4-5).

There were no P's in any column but STS (T) periodically flicked on/off for each of the satellites listed with a LVL value.

During the test the Lat/Lon remained at zeros, showing that it simply couldn't get a lock on my position with only 3 weak satellite signals.

A further drive but this time watching the sensors screen showed no pulses and speed remained at zero throughout.

I interpret this to be a double whammy issue then, a combination of broken speed sensor and the GPS signal reception.

When it goes into the Toyota garage next week I'm going query more detail on the software updates, I got the impression they were firmware updates not related to the DVD. They had mentioned that one took 40 minutes to complete and the main comments were around the dash speedometer reading rather than SatNav.

[shcm]

I interpret this to be a double whammy issue then, a combination of broken speed sensor and the GPS signal reception.

Well you might be lucky in that it's just both the GPS antenna connector and the connector with the vehicle speed signal on, not being seated properly in the back of the satnav. Possible, I suppose, if somebody has previously had the satnav out(?) and been careless putting it back. Connectors are very often the weakest link, but I don't want to give you false hope.

When you are in diag mode, do you get any response from the handbrake and reverse signal test? Both those signals are on the same connector as the vehicle speed input.

For the GPS side of things, you might have something like a duff GPS antenna. You don't have anything large and metallic on the dash do you? Or excessive window tinting? (although, you shouldn't have that on the windscreen). Both can reduce the GPS signal level getting to the antenna. I have a metallic backed windscreen sunshade and when I turn the sat nave on with it in place, if I check the GPS sig level, it is severely reduced. (Clearly, the shade is not in place when driving ).

It could be a whole heap of things. Another could be one of the internal power supplies (PSU) has failed inside the sat nav. Very often the GPS antennas are active (i.e. powered, but I haven't check this one) and the satnav will provide it with power as a DC feed down the coax. One of the internal PSU failing could also explain both I/O failure (speed sig) and poor GPS reception. Anyway, it's wild speculation without examining the unit.

The unit also store DTCs (trouble codes), we might not be able to decode them, but have a look to see if any are stored. Very often there will be a few anyway, so you may have to clear them (press and hold MCLR???, sorry can't remember exactly) and then see if any return immediately after clearing the codes and putting the unit back into normal mode.

Another thing you could try, is disconnecting it from the supply (probably disconnecting the Battery is easiest, if you don't want to remove the unit), leave it 15 minutes, reconnect, then try rebooting. (It will need the map DVD in for that). I suppose there is the risk it may not start up at all, but then it's another indicator that the satnav is the problem, not elsewhere.

They had mentioned that one took 40 minutes to complete and the main comments were around the dash speedometer reading rather than SatNav.

So, it sounds like they are trying to clear the problem, by upgrading powertrain and body ECU firmware. I wish I had that power of diagnostics (, please excuse my sarcasm).

Well perhaps it might resolve it, but there's two indicators pointing to a common unit, so I'm very skeptical.

[Joylove]

Excellent tips above.

I would think the GPS antenna would be a dedicated coaxial type, with 3V or 5V on it for the GPS LNA. The other signals (speed, handbrake) would be on a different connector.

Since you have 3 satellites, you have a working GPS receiver with a poor signal. Dead antennas or dead receivers usually equate to 0 satellites received; Almanac not decoded.

Get into the dash and see if the antenna has moved or been moved, or the wiring damaged by careless mechanics.

Check the multiplugs on the back of the radio too, although on a car that modern; do not all signals come over a databus, hence things like handbrake, average MPG, average speed and more would also be missing if the canbus was disconnected? Perhaps shcm will know that one.

[shcm]

The other signals (speed, handbrake) would be on a different connector.

Yeah, that's what I said wasn't it?

Since you have 3 satellites, you have a working GPS receiver with a poor signal. Dead antennas or dead receivers usually equate to 0 satellites received; Almanac not decoded.

Get into the dash and see if the antenna has moved or been moved, or the wiring damaged by careless mechanics.

Clearly there is a loss of sensitivity in the RX chain and yes, it may well be (and I hope it is) that simple. On the other hand, RF @ 1.5GHz is slippery stuff. For example, it can leak around a failed LNA after the patch antenna (result=low sensitivity, not zero signal). For a simple class A BJT LNA, an out of spec power supply would result in changed Ic (Result=changed S21, i.e. change in sensitivity). The list goes on..........

Check the multiplugs on the back of the radio too, although on a car that modern; do not all signals come over a databus, hence things like handbrake, average MPG, average speed and more would also be missing if the canbus was disconnected? Perhaps shcm will know that one.

No, they are discrete signals as I said. Reverse, handbrake and vehicle speed are on a 5 pin connector. It doesn't have CAN or flexray or LIN or....... It just has Toyota's AVCLAN, which is just an audio control bus.

[Joylove]

Wasn't sure if they went to full canbus on the 4.3 being a 4.2 owner. As an aside, could I fit a 4.3 nav in a 4.2 and maintained mpg and outside temp sensor support?

It does sound like a duff LNA in the GPS antenna is more likely than a dead GPS receiver in the nav drive itself. The connector will probably be an Alpine or Panasonic compatible Tyco part, and a replacement could be purchased from eBay with careful attention to the voltage and connector. Most LNAs are 3V/5V compatible these days but it need to be checked.

I am betting on damage to the wiring though from a pinched harness during installation.

[Zathras]

Thanks everybody, great information and tips. Special thank you goes to shcm for a direct hit! (explain in a moment)

Firstly the sensors; the reverse, speed and hand break simply do not function. From the comments above I'm guessing the connector is either duff, fallen out or was never reconnected properly. I suspect they were never working as I'm sure the dead reckoning was duff from the outset but with a good GPS reception generally it was never really a problem.

The console has only been out once and that would have been for the dealer/factory fit of the toyota audio sub under the seat. I was unhappy with the cars condition when it arrived new for a number of reasons, such as the bass was turned to full, the wiring under the seat vibrated on the sub, clips on the roof were missing and it had a generally less than quality finish overall.

So I would not be at all surprised if this shoddiness was replicated in the work behind the console and the connection was simply never plugged back in, but this is only coming to light now due to the GPS signal issue.

For the GPS side of things, you might have something like a duff GPS antenna. You don't have anything large and metallic on the dash do you? Or excessive window tinting? (although, you shouldn't have that on the windscreen). Both can reduce the GPS signal level getting to the antenna. I have a metallic backed windscreen sunshade and when I turn the sat nave on with it in place, if I check the GPS sig level, it is severely reduced. (Clearly, the shade is not in place when driving ).

So onto the GPS and shcm you scored a direct hit, although it wasn't as simple as you might think. I had fitted a CrashCam to record my journeys on a small camera which does cycle recording, the idea was that it could be useful in any insurance claims. It has been in the car for over a year and the GPS has only been a problem for the last couple of months so it didn't ring any alarm bells originally.

However, it has been moved around the windscreen over this time and is now located just under the GPS aerial. Now get this though, while it is off there isn't a problem. While it is on, there isn't a problem. While it is recording, there isn't a problem. But while taking from the cars power to charge its internal Battery, BANG! down goes the GPS reception! The GPS can be locked onto seven satellites with four or more levelling in the twenties, but when the camera starts charging it drops to a struggling 1-4 satellite lock with reception all below 5.

I've confirmed it isn't the wiring of the charging cable by using a small mobile Battery based charging device, it is genuinely the camera's charging circuits causing interference. I'm guessing that the reason it has only recently been a problem and slowly getting worse is because the internal Battery has nearly died meaning it is now more often drawing power to charge itself.

After some fun experimenting with tin foil hats I've now wrapped the internal electronics in foil which although doesn't stop the interference completely, no longer causes much of an issue to the reception. Problem solved.

The car is still booked in next week for work and I'll get them to look at the sensor issue then.

Thanks everyone for your help, I've learned a lot from this thread.

[Joylove]

Wow, some crazy coincidences there, especially with the charging circuit! A little trick I've learned is that 20-47pF across the SMPSU coil will drastically reduce most of that GHz range noise.

Are you able to move the antenna to one side if the camera is in its final position?

One day in built up or heavily wooded areas you may find signal problems, where a few dB of signal (especially with dead reckoning not available) makes enough difference to lose position again.

[shcm]

Low ESR/ESL output caps tend to help. Generally, the input generated noise is worse on a buck reg than the output.

[Davrav]

Low ESR/ESL output caps tend to help. Generally, the input generated noise is worse on a buck reg than the output.

And once more in english............................

[shcm]

ESR = equivalent series resistance

ESL = equivalent series inductance

caps = capacitors

buck reg = buck regulator = dc to dc switching voltage regulator (buck is a voltage down conversion, boost = up conversion).

but hey! I didn't start it! :D.

[Big Kev]

ESR = equivalent series resistance

ESL = equivalent series inductance

caps = capacitors

buck reg = buck regulator = dc to dc switch voltage regulator (buck is a voltage down conversion, boost = up conversion).

but hey! I didn't start it! :D.

....aye...but obviously YOUR HOME DISTILLED SNAKE OIL is 40% by volume......who is Michael Farad anyway....? One of The Shadows, Marvin, Welch, and Farad...?

Lost Kev

[shcm]

....aye...but obviously YOUR HOME DISTILLED SNAKE OIL is 40% by volume......who is Michael Farad anyway....? One of The Shadows, Marvin, Welch, and Farad...?

Didn't the shados go on to form UFO? (Like the silver suits, but not sure about the purple hair styles). Then of course Gerry Anderson went on to be a founding member of Yes.

(Get all my accurate information from uncyclopedia.com - enhanced with a little snake oil)