Speed pulse on 110 300 TDI

[stobbie]

I have an older becker radio/gps system in my 110, the radio is excellent but I have never used the gps because I don't have a speed signal for it.

I don't want to spend much money on this older system, I have a Tom Tom in my disco, but it would be nice if i would get the becker to work.

All available pulse generators cost too much.

I was thinking about glueing one or two magnets on the hand brake drum, and put a hall sensor just above it. Do you think I could use the pulse out from the hall sensor directly on the speed pulse in from the becker?

[Sean]

I have an older becker radio/gps system in my 110, the radio is excellent but I have never used the gps because I don't have a speed signal for it.

I don't want to spend much money on this older system, I have a Tom Tom in my disco, but it would be nice if i would get the becker to work.

All available pulse generators cost too much.

I was thinking about glueing one or two magnets on the hand brake drum, and put a hall sensor just above it. Do you think I could use the pulse out from the hall sensor directly on the speed pulse in from the becker?

it would be very easy to do - but how do you propose converting it to a usable MPH figure as it would JUST tell you how fast the drum was rotating ?

[stobbie]

it would be very easy to do - but how do you propose converting it to a usable MPH figure as it would JUST tell you how fast the drum was rotating ?

I don't think the gps needs a usable mph figure, I think it calibrates it self using gps information or am I wrong?

[LandyManLuke]

Why does it need a speed sensor? is it just to deterimine that the vehicle is moving or not?

GPS will give speed info, so there's no direct need for it, unless it's for some sort of cross correlation.

[stobbie]

I think it is used for when driving in tunnels or something, I just know the older units will not work without this pulse connected.

If I have the pulse, I can also fit a cruise control to that same pulse.

[FridgeFreezer]

I'd just use the electronic speed transducer from a RR or Disco, there are some that fit in-line with the speedo cable and some that bolt directly in place of the speedo cable on the transfer box.

Speedo drive ratios have been covered here before, a search should turn up the info you need.

[stobbie]

It's working now! I've glued a little magnet on the hand brake drum, and have put a reed relais on a bracket a few millimeters above it. Very simple, very cheap!

[western]

hope you've got lots of speare magnets, it might dropof at some point.

[steve_d]

hope you've got lots of spare magnets, it might drop of at some point.

I think you will find the reed switch will not last long either.

Steve

[stobbie]

hope you've got lots of speare magnets, it might dropof at some point.

That is a possibility, magnets are cheap :-) . I've glued the magnet into the recessed area of the drum so it won't be the first thing that is hit, also I almost don't use the car offroad. The magnet seems very thight, I have used SUPERglue.

I think you will find the reed switch will not last long either.

Steve

That is also a possibility. Depending on how long it's gonna last I may replace it with a hall sensor at some point, the price of that is almost the same as a reed switch.