Speed Pulse

Glynanderson · Post by **Glynanderson** » Wed Oct 18, 2006 4:21 pm

I'm trying to fit a Sat Nav system that requires a speed pulse.
I thought I could use the SP+ from the back of the speedo (after the convertyer chip) but this doesnt seem to work.
Anyone else had this done or can offer any help?
Cheers (again)
Glyn

David Edwards · Post by **David Edwards** » Wed Oct 18, 2006 6:15 pm

Sorry got my sat nav on my nokia 6630. Good hunting and happy motoring.

ferdyb · Post by **ferdyb** » Wed Oct 18, 2006 7:54 pm

Glyn, what sort of sat-nav needs a speed pulse off the vehicle? A sat-nav knows where it is to within a couple of yards and what speed it is doing to within about 0.03% I believe. Much more accurately than any vehicle speed indicator could ever be, so what's the point?

ferdy

Glynanderson · Post by **Glynanderson** » Wed Oct 18, 2006 8:04 pm

Hi,
A sat nav uses the speed pulse to helpout when there are no satellites available, seems to be mostly the older ones, although some of the newer models which don't 'need' a speed pulse still have the option to add one.
It is also used to control the GALA (Geschwindigkeitsabhängiger Lautstärkeanhebung) speed dependant volume.
Bottom line is, it won't work without it!
Cheers,
Glyn

grumpo · Post by **grumpo** » Wed Oct 18, 2006 9:07 pm

The majority of fitted satnav systems use a speed sensor pulse
and small gyros to predict the speed and direction when in long
tunnels and where tall buildings block the view to the satellites.

The frequency of the speed sensor does not matter as the system
calibrates itself to actual speeds when satellites are available.
All the systems I know of will run normally without a speed sensor
but maybe there are some that don't.

It is best to connect the satnav unit directly to the gearbox
output available directly behind the instrument panel, however,
some systems have a lower impedance than others and can cause the
hold light to flash due to excessive current drawn from the gearbox
sensor supply. If this happens, you can fit an amplifier to avoid
these sort of problems.

The output from the gearbox is a square wave as distinct from a
sine wave and usually there is a menu setting in the satnav to
select the type of speed signal.

owelly · Post by **owelly** » Wed Oct 18, 2006 10:06 pm

I foud a speed sensor wire tucked up behind the glove box. Pull the glove box out and release the wiring loom from the clips and look for a single wire with a label on it.
HTH

Glynanderson · Post by **Glynanderson** » Thu Oct 19, 2006 8:27 am

Hey!
Thanks for the replies.
I'll look for the wire behind the glove box, nice one Owelly.
Also, I was worried about taking the pulse from before the converter as the unit would then be receiving kilometer information, but if Grumpo is right (and I'm sure he is) then the unit should calibrate the pulse to match the speed of the vehicle.
I was getting a reading from the pulse wire that I was originally using, but maybe the converter chip weakened it somehow so that my Blaupunkt unit couldn't read it.
Also, it seems to be an AC signal!!??
Thanks again!
Glyn

Glynanderson · Post by **Glynanderson** » Thu Oct 19, 2006 10:48 am

Hi Owelly,
I had a look for the wire behind the glove box, couldn't find one though, although there is a fairly thick white wire on it's own over to the left, it has a female spade connector on it.
Any chance you could be a bit more specific about where it is and the size and colour.
Cheers,
Glyn

ferdyb · Post by **ferdyb** » Thu Oct 19, 2006 11:03 am

Oh, I see, never knew that! You learn something new every day still, even after all these years. Could explain why some of them are so expensive then.

ferdy

grumpo · Post by **grumpo** » Thu Oct 19, 2006 11:31 am

There are some very important differences between the various systems
available, which is why you should be aware of the functionality of the
proposed purchase.

Cheap becomes expensive when you throw it in the wheelie bin.

CarAudio_James · Post by **CarAudio_James** » Sat Oct 21, 2006 10:27 am

Go through the supplier of hte unit, or direct to blaupunkt

They will have access to a trade database giving precise veichle info on where to get this.

Blaupunkt are on 01895 838880

hope this helps

motorwizard · Post by **motorwizard** » Sat Oct 21, 2006 1:53 pm

The connection from the speedometer goes to the gearbox ecu. It should be possible to trace this wire. The jap GPS I had with my van was connected to this wire

white van man · Post by **white van man** » Sat Oct 21, 2006 3:27 pm

speed pulse and reverse can both be done off of main ecu,normaly done this way in japan,wont make any difference what side of the converter chip and in my opinion from seeing more and more hold light faults occuring with them id bin it and fit a face!!!

egor110 · Post by **egor110** » Sat Oct 21, 2006 4:01 pm

I've got a garmin c310 which i'm really pleased with, best £159 i've ever spent.
Just plug into cig lighter, switch on, stick in posrcode and off you go , it's really reliable and i've always got to the destination within 5 mins of the estimated time of arrival.

owelly · Post by **owelly** » Sat Oct 21, 2006 8:22 pm

I'll have a look tomorrow when I give the Freda it's weekly (yeah, righto) check-up....

Speed Pulse

Speed Pulse

Picking up Speed Pulse

speed pulse