HELP! bought a Sat Nav, where is the speed sensor?

[madfads]

I'm new on the board (hello), I need to know where the Speed Sensor wire is (or sometimes called the Reluctor).
I think it is on the 6th pin of the ECU, but right now I don't even know where the ECU is.
I have a Blaupunkt DXR-52 sat-nav installed but this is the last wire to go in, it needs it before it can work properly.
I also need to wire in the reverse light, I am thinking that this can be done by splicing the reverse light wire near the light itself and bringing a wire back, any suggestions that may be easier?

Thanks,
Keith.

[Leadfoot]

ECU is the black box slung on top of the battery (at front of passenger footwell).
Speed sensor lives above & just in front of the diff.

[shpub]

You may also find that the speed sensor is not necessarily compatible with Sat Nav systems. Splicing directly onto the sensor may disturb it electrically so that it produces no output. Some cars have a conversion box which converts the pulse train as well so getting on the wrong side will give the wrong information. It may also not generate any pulses at low speed> not a problem normally but screws up Sat Nav. In many cases, the only cure is to fit a second dedicated speed sensor.

Steve
www.tvrbooks.co.uk

>> Edited by shpub on Thursday 18th December 17:08

[madfads]

Thanks for that, I just had a look and its there alright. Still not quite sure what wire the speed sensor is though. Or where the reverse light wire is....any more ideas?

[david beer]

I tried the speedo pulse, it doesnt register until around 6-8mph. You can buy an amplifier but they dont work below 3mph. The only answer is to fit a seperate one.

[joospeed]

why can't the sat nav detect you're moving from GPS? it can't possibly rely on inaccurate speedo senders for movement info? ..

[moschops_72]

joospeed said:

why can't the sat nav detect you're moving from GPS? it can't possibly rely on inaccurate speedo senders for movement info? ..

This systemn is a back-up, i.e. if you lose contact with the sattelite, it knows of your last whereabouts, and working with your current speed, it could still give approximate guidance.

Jeff

[joospeed]

OIC . thanks

[madfads]

I had a chat with David Batty from "The Garage" TVR specialist and he reckons I should try the TVR speed sensor first. He thinks the Sat-Nav may boost the signal just like the ECU does. I am going to give it a try anyway and see, the Sat-Nav will calibrate the sensor anyway so it may work. I guess if it doesn't register speed below 6mph then it's not so bad, I mean how often do you do <6mph on long journeys? It would only be a problem if you lost sattelite connection for a while and you were also doing <6mph for a while too. I will try it today and post a reply to tell if it works. K

[TVRinBFG]

I think this particular unit checks with the satalites every 30 seconds for latest position. You therefore need the speed sensor information to let the car's unit know how far you've moved in that time (and like the chap above says, if the unit can't get a signal from the satalites for any reason).

However, the TVR speed sensor tends not to read below 15-20 mph; and at upto 20 mph in 30 seconds you can easily miss your turning, if you are in a big city. What you need is the extra unit from Blaupunkt that reads a strip, that's stuck or painted on to one of the tyres. And you have to keep re-sticking or painting this! This is more accurate than the speed sensor slpicing.

I had the Blaupunkt unit on one of my Cerbies. How much you pay for the head unit if you don't mind letting me know?

[madfads]

I paid £470 (reduced from 900 I think), www.bluespot.co.uk/stock/dxr52_s.asp

I will try the splice and see, I may get lucky, if it doesn't work I will buy the other sensor I suppose :-(

Cheers

[david beer]

Clarion sell a magnetic sensor, you rub half the tyre to magnetise it and the sensor then sits nearby. Trouble is they are only good upto 90mph when it goes a bit wobbly. A company called sales marketing do a drive shaft sensor, £50 i think.

[madfads]

Well I made a go of finishing off the installation yesterday. I found the speed sensor wire, it comes from the back of the car under the centre console (2 wires, black and grey) I spliced the grey one and it worked. I also had to wire the reverse light in there too. It seems to work fine, it did miss one turn though, but it realised it and told me to turn back. The Blaupunkt DXR-52 calibrates the speed sensor automatically, you have to drive it while it does this. So it may boost the signal like the ECU does. I reckon its a good option for sat-nav on a TVR.
Im off home today on a big drive to Holyhead so it will be very useful (I'm from Dublin).
Happy xmas everybody.
Keith.