E39 Prewired for Navigation?

willy_manily · #1 02-18-2010, 06:01 AM

Quote:

Originally Posted by KiwiJochen

You can do this much easier:

Reverse signal: take it from the reverse light in the taillight cluster, it is right behind the nav location. Tap into the reverse light wire.
It is the same as the reverse signal from the LCM, except for the rare occasions when reversing with a trailer attached, and with the original trailer wiring control unit fitted (because then the reverse light is turned off)

Wheel pulse: if you have EDC, then take it from the EDC control unit behind the battery. With no EDC, you can use the averaged wheel pulse (slightly less accurate but works) from the radio module, right beside the nav

This way all the work is in the boot, you don't have to run any wires to the front of the car at all.

Apparently i only need to do this if i'm worried about using the car in an underground carpark or something like that, where there is no GPS signal.

Is this true?

neiloakley · #2 02-18-2010, 09:30 AM

Quote:

Originally Posted by willy_manily

Apparently i only need to do this if i'm worried about using the car in an underground carpark or something like that, where there is no GPS signal.

Is this true?

Just do it properly and use the reverse and wheel speed signal. If you dont you will only regret it.

Yes you could 'manage' without them, but the nav computer uses signals from these plus the gps and the gyro to give a smooth display. It's not just underground carparks, it's in bad weather too, or tunnels, or in built up areas.

Its two wires, spend the extra 30 minutes doing the job properly. Dont bodge it. I've given the wiring diagrams, plenty of people have said the easiest location to get the signal sfrom so please take the advice.

KiwiJochen · #3 02-18-2010, 01:37 PM

Quote:

Originally Posted by willy_manily

Apparently i only need to do this if i'm worried about using the car in an underground carpark or something like that, where there is no GPS signal.

Is this true?

The speed pulse is needed for dead reckoning

Dead reckoning is used...

for the first seconds to minutes after switch on before a GPS signal is acquired (you can easily drive 1km in this time)
under bridges
in tunnels
in underground carparks
in built up cities with many skyscrapers and poor satellite reception
in very bad weather with weak GPS signal
and many other situations where GPS signal is interrupted.

Use at the VERY LEAST the speed pulse!

The reverse signal is only for when you go backwards.... but that is so easy to connect, there is no excuse for not using it.

No Dead Reckoning = Disappointing GPS performance

With Dead Reckoning = Perfect GPS Performance

You choose.

Chalky · #4 05-17-2014, 06:00 AM

Quote:

Originally Posted by KiwiJochen

The speed pulse is needed for dead reckoning

Dead reckoning is used...

for the first seconds to minutes after switch on before a GPS signal is acquired (you can easily drive 1km in this time)
under bridges
in tunnels
in underground carparks
in built up cities with many skyscrapers and poor satellite reception
in very bad weather with weak GPS signal
and many other situations where GPS signal is interrupted.

Use at the VERY LEAST the speed pulse!

The reverse signal is only for when you go backwards.... but that is so easy to connect, there is no excuse for not using it.

No Dead Reckoning = Disappointing GPS performance

With Dead Reckoning = Perfect GPS Performance

You choose.

Jochen is right, initial time to find a satellite fix can be considerable, and with speedo/wheel signal your nav computer will be useless for that period, instructions will be rubbish. I experienced this last week in my own car (E38 nav retrofit), it was embarrassing. Then, I connected up the speedo signal (TAA), and I was very impressed. I suddenly had navigation directions immediately available upon entering the car, prior to getting proper GPS fix! The nav computer's tracking based on speed signal, compass, & gyros is quite amazing. It really was like another upgrade to my nav. Love it.