Nav "number of feet until turn" inaccurate

[Norwegian33]

I had oem nav retrofitted into my E46 03' 330xi a couple of months ago and had purchased a remanufactured MkIV from Bimmernav. Since it's been installed I've had the following issue:
Navigation has been telling me that I have 500 feet until a turn, when it's really more like 50 feet, or 100 feet until a turn when it's more like 10 feet. Thing is, once I get to the turn (or the corner,) it tells me quite accurately to turn when I should be turning (and the number of feet correctly says, "0") It's just over the last 500 or so feet before I get to to a turn that the distance it's telling me to go before the next juncture- is inaccurate. And throughout this all, the arrow always seems accurately placed on the map, so it does in fact seem to correctly know exactly where I am. Funny how if I just take a zero off of the end, it would seem to be correct.. I'm wondering now if it has something to do with faulty wheel speed sensor(s) Anyone heard of this or experienced it? Thanks..

[trapdoor]

When I had the retrofit done in my E46, I had exactly the same issue - in a nutshell, it transpired that the retrofit loom as supplied by BMW had a wiring error whereby the wheel speed sensor pin the the connector that attaches to the Nav Computer wasn't in the correct 'hole' in the connector shell. IIRC it should have been in pin 11 but was in pin 10 or perhaps the other way round.

Check the WDS for the correct pinout on the Nac Computer for the Wheel Speed sensor (or do a search here as I'm sure it's been posted before) and then cross-check with the wiring you have in your loom.

Once it was swapped over on mine, the accuracy to turns/junctions etc worked perfectly.

HTH.

Edit: Just found the original article re. this issue:

http://www.xoutpost.com/articles/all...formation.html

[KiwiJochen]

That is a very plausible reason!

the dead reckoning used by the nav allows it to be deadly accurate

So if the dead reckoning is missing, the displayed accuracy will reduce hugely.

[Norwegian33]

Originally Posted by trapdoor

When I had the retrofit done in my E46, I had exactly the same issue - in a nutshell, it transpired that the retrofit loom as supplied by BMW had a wiring error whereby the wheel speed sensor pin the the connector that attaches to the Nav Computer wasn't in the correct 'hole' in the connector shell. IIRC it should have been in pin 11 but was in pin 10 or perhaps the other way round.

Check the WDS for the correct pinout on the Nac Computer for the Wheel Speed sensor (or do a search here as I'm sure it's been posted before) and then cross-check with the wiring you have in your loom.

Once it was swapped over on mine, the accuracy to turns/junctions etc worked perfectly.

HTH.

Edit: Just found the original article re. this issue:

http://www.xoutpost.com/articles/all...formation.html

okay, thanks, I'll definitely take it under consideration. When I clicked on the link you included, the Administrator who posted the issue said he wasn't getting any wheel sensor readings before he made the switch. I went under my service menu this morning, and I am in fact getting wheel sensor readings. When stationary, the number reads "0" and when I started moving, the number started rapidly increasing, just as it's supposed to, so I'm wondering if this is really the issue or not.. I'll definitely check it out though. Thanks..

[KiwiJochen]

Have you got NavCOder?
Try reading out the System Parameters of the nav, this will be interesting to compare with a normal nav.

[big bob]

I believe that in the absence of a wheel speed sensor, the less accurate GAL (vehicle speed) signal is used. Not sure how you tell from the sevice menu if this is happening.

[KiwiJochen]

Originally Posted by big bob

I believe that in the absence of a wheel speed sensor, the less accurate GAL (vehicle speed) signal is used. Not sure how you tell from the sevice menu if this is happening.

Nope. The nav only reads wheel sensor pulses from the wheel sensor input

You can connect the ABS signal (instantaneous wheel speed) or the averaged speed output (as used for the GAL function for the radio)

To the OP: check if you have GAL-signal or ABS signal connected.
Maybe you have GAL, and the averaging of the speed signal is causing problems.
If you have GAL, change to the ABS signal and the problems will likely disappear

[Norwegian33]

Originally Posted by KiwiJochen

Nope. The nav only reads wheel sensor pulses from the wheel sensor input

You can connect the ABS signal (instantaneous wheel speed) or the averaged speed output (as used for the GAL function for the radio)

To the OP: check if you have GAL-signal or ABS signal connected.
Maybe you have GAL, and the averaging of the speed signal is causing problems.
If you have GAL, change to the ABS signal and the problems will likely disappear

Sorry its taken me soo long to get back to this thread. Now how in the world do I check if I have the GAL or ABS signal connected? and how would I change reverse/change this setting? I went through every setting in the hidden menu and can't see where this is done.. Thanks.

[KiwiJochen]

Originally Posted by Norwegian33

Sorry its taken me soo long to get back to this thread. Now how in the world do I check if I have the GAL or ABS signal connected? and how would I change reverse/change this setting? I went through every setting in the hidden menu and can't see where this is done.. Thanks.

Quite simple.
Look at the purple connector on the nav computer

What colour wire is connected to pin 10?

Black/white = TAA
Yellow/red = abs speed pulse, front left
Yellow/white = abs speed pulse, front right

Another way to tell is to look at the frequency of the speed pulse.
Roll the vehicle forward at walking pace or less.
Does the displayed speed pulse climb quickly to a value >10? Dies it stop and change quickly when you stop the car? then it is abs pulse (non-averaged)?
From memory, 50kmph is around >100 on the speed pulse display.

If it takes time before it starts to climb, and time to reduce, and shows low value, then it is averaged TAA pulse.