Am i tapping one cable or two for the reverse light?

Not sure mate, my retrofit loom just plugged into the OEM looms plug and play.

I think kiwi knows where to find the speed wire in the trunk. Ask him or do a search for his post on this. The big white plug with the 4 wires I think is X1532 and pin 1 is the RT/GN power and goes to nav blue plug (X1313) pin 1. Pin 2 BR is ground and goes to blue pin 10. Pin 3 is I-bus WS/GR/GE and goes to blue 3. Usually the adapter cables have a mate plug to attach to X1532. Go to Google and search for WDS and spagetti as it is a site that has the WDS wiring info, other sites for WDS also. When there you can look up your car. The Items of interest are A112 Nav, A197 video module, N9 radio etc. The nav antenna is cheap on ebay. Autotronics is an expert in OZ and kiwi another expert in Switzerland ex NZ and he knows a lot about e39s in OZ and NZ. You may want to investigate the cables with the following P/Ns as they may be of help. 61 12 9 413 963, 61 12 6 907 842, and 65 90 0 017 296. Also ask your Dealer parts guy to look up the installation instructions on his computer for you and see what they show as they may help P/N 01 29 0 028 309 and 310.

All others rview my post and correct any mistakes.

KIWI tells me that i do not have to run a cable up to the dash as the Speed Sensor and the reverse sensor are up the back attached to the radio unit.

Is this the case?

Any update on this?

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.

These may help you

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.

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.