Speedometer sense

[s5tuart]

I am fitting a Blaupunkt Travelpilot E2 in-dash CD/navigation system into my 500 Chim.
The unit has GPS but also, because of the older technology I guess, needs a speedo sense input.
Has anyone got any idea of where I can find the pick-up point for this, or is there a ECU point where I can get it from?
Many thanks in advance.

[chim666]

I can't see how the output from a relatively inaccurate speedo sensor could be of any use to a Sat Nav, when it has GPS anyway. It would also be reliant on tyre diameter/profile.

But, seeing as you asked: the Chimaera's speedo sensor is tucked away on top of the O/S rear axle. There's a twin pin plug that you might be able to intercept.

[s5tuart]

I can't see why either, but that's what Blaupunkt Technical are saying! Beats me! Thanks for the pointer.
Can I tap off the ECU anywhere do you think?
Thank you

[chim666]

s5tuart said:

Can I tap off the ECU anywhere do you think?

Probably, but I don't know where. Maybe someone will be along soon who can answer that for you.

[spend]

chim666 said:

I can't see how the output from a relatively inaccurate speedo sensor could be of any use to a Sat Nav, when it has GPS anyway.

When you get lost in tunnels with turnings like Leeds City Centre you will know why it needs it

Dave

[nicktowe]

The higher end sat navs use dead reckoning to assess the position of the vehicle, if it loses a satellite fix, ie, near tall buildings in tunnells. Many factory fit satnavs use steering angle and road speed to assess the cars position. That way if they lose satellite signal they can still give directions. Also if the unit knows where it is it can re-acquire the satellite signal much faster.

Edited by nicktowe on Monday 2nd July 18:27

[softtop]

nicktowe said:

The higher end sat navs use dead reckoning to assess the position of the vehicle, if it loses a satellite fix, ie, near tall buildings in tunnells. Many factory fit satnavs use steering angle and road speed to assess the cars position. That way if they lose satellite signal they can still give directions. Also if the unit knows where it is it can re-acquire the satellite signal much faster.

Edited by nicktowe on Monday 2nd July 18:27

my PDA uses this facility with Tom Tom software.

[biggiles]

softtop said:

nicktowe said:

The higher end sat navs use dead reckoning to assess the position of the vehicle, if it loses a satellite fix, ie, near tall buildings in tunnells. Many factory fit satnavs use steering angle and road speed to assess the cars position. That way if they lose satellite signal they can still give directions. Also if the unit knows where it is it can re-acquire the satellite signal much faster.

Edited by nicktowe on Monday 2nd July 18:27

my PDA uses this facility with Tom Tom software.

My Nokia phone has the TomTom software too- but how did you tie it in with the speedo/CAN bus??!

To the previous poster- the wheel diameter shouldn't make a difference as the satnav unit will be able to work out a diameter ratio from the first journey, based on the GPS movement and the speedo ticks.

[paulathome]

s5tuart,
The speedo sensor wires run along the center console from just above the diff along the passenger side and then up into dash.
If you remove the screw under the little tray at the back of the center console and lift the console you should see two little wires which come up through the floor above the diff. There should also be a two pin connector which is in series with this cable.
You could take a signal from these wires as long as the input impedance of the
GPS receiver is fairly high otherwise you may load the speedo sensor circuit to much and may stop the speedo itself from working.
Hope this helps.
Paul.

[s5tuart]

BRILLIANT Paul! Thanks for the info. I don't suppose you know if these wires pass through the radio compartment on their way to the speedo do you? That would make life very easy!!
In response to some of the other posts, the unit also has a little gyroscope built in, I guess to enhance positioning info (good point about tunnels!) and to determine where the car is turning etc. The fitting instructions also require that I do a 'calibration run' of at least 30 miles, so that would agree with Biggiles post.
I know my old Tomtom used to get 'lost' in London when there were tall buildings around.

Edited by s5tuart on Tuesday 3rd July 06:57

[Ribol]

My speedo(2000 X reg Chim) takes its signal from a box in the dash top, when I fitted my Pioneer satnav I took the pulse from there.
The unit calibrates itself automatically after driving a bit, making the speedo on the satnav more accurate than the TVR one.

HTH

[s5tuart]

Thanks Ribol.
Can you give me a clue as to what the box looks like and positioning please? Left/right/centre etc. Mine is a 1998 500. Thank you. Stuart.

[Ribol]

s5tuart said:

Thanks Ribol.
Can you give me a clue as to what the box looks like and positioning please? Left/right/centre etc. Mine is a 1998 500. Thank you. Stuart.

On my car(2000 X reg) it is a black box, fag packet size(ish) with a white plug facing the right hand side of the car, behind the two ally heater wheels towards the bulkhead, not hidden in any way.

I may have a pic of that general area somewhere, if you feel that may help, PM me your mail address and I will try and find it for you.

[Ribol]

Stuart, YHM