Irratic Speedo...Confused Navi.

[Tokyokev]

Not sure if those of you with Navi systems have the same problem but...due to some irratic Speedo needle actions...i.e. it blips a bit to the 20-30km mark when I stop at traffic lights etc. The direct result of this is a Navi that thinks I am 100 or so metres further ahead than I actually am in reality.

So I am getting some wierd directions from the on board screen and as the streets in Tokyo are so damn small and complex, it's proving difficult to find my way around. So I get lost. A lot. And I mean really lost. Like no one can hear me scream kind of lost.

If there is an easy fix, would be great. I know the speedo thingy is attached to the diff...but where? Maybe a simple claen will help...or is it electronic? Is there another palce to connect the Navi speed device?

Any advice would be great, as I am wasting a lot of fuel getting lost.

Best

K

PS: I get the car back tomorrow after 3 weeks in the shop...fixed clutch and full service, brakes etc. Also worked up the balls to remove the rear box and now have straight through pipes Still got the cats on...but daaaaamn it sounds sweet. I would say a lot like a 355 with a Tubi at mid revs. For your entertainment and mine, I am planning to record a short video of a midnight run around the famous Route246 in Tokyo, am hoping to recreate the Grand Turismo 3 circuit on Playstation. (And I promise not to put any musical soundtrack over the live sound.) Also will try not to lose my license in the process.

Edited by Tokyokev on Tuesday 5th December 05:21

[mike_e]

The hall effect sensor is mounted at the rear of the diff, can't remember which side but I think it's the nearside. Looked for the toothed rotor attached to the inside of the CV joint. Sensor is mounted horizontally, pointing towards the front with two wires sticking out the back.

If you've had a satnav fitted that takes a feed from the sensor then this may be the root cause. You may be getting electrical noise introduced from other parts of the car.

[jensena]

Must admit, I've never heard of a Sat Nav system that is connected to the speedo. My Sat Nav system also tells m what speed I am doing, and its probably a lot more accurate than the speedo.

[southendpier]

jensena,

to explain, my factory fitted system in my daily jag uses GPS - but when a signal is not availbale - tunnels or tall buildings (ie Tokyo i guess) then it resorts to using the speed of the car to work out where it is until the "satellite" is found. (is it satellites or phone masts, cant remember?)

I guess this is the prob toykyokev is experiancing

[Tokyokev]

southendpier said:

jensena,

to explain, my factory fitted system in my daily jag uses GPS - but when a signal is not availbale - tunnels or tall buildings (ie Tokyo i guess) then it resorts to using the speed of the car to work out where it is until the "satellite" is found. (is it satellites or phone masts, cant remember?)

I guess this is the prob toykyokev is experiancing

Spot on David. I was initially told it needed calibrating etc...but after several resets and only after much guess work and some common sense...I figured it was some sort of speed sensor problem; especially as the only thing that is visibly wrong is the speedo behaviour.

On open highways when the speedo is mre stable, and when the unit depends on GPS alone, then I do not have a problem with it...i guess I will have to clean up the hall effect sensor and hope it fixes it...or buy a road map and take a step back into the 19th century.

thanks for the advice.
K

[mad mark]

My speedo used to jump about all over the place, but only when stationary. I didn't give it much thought untill i noticed that whilst sitting at trafic my odometer was climing.

Try giving the sensor and the rotor a clean first then adjusting it closer to the toothed rotor.

[jensena]

Tokyokev said:

southendpier said:

jensena,

to explain, my factory fitted system in my daily jag uses GPS - but when a signal is not availbale - tunnels or tall buildings (ie Tokyo i guess) then it resorts to using the speed of the car to work out where it is until the "satellite" is found. (is it satellites or phone masts, cant remember?)

I guess this is the prob toykyokev is experiancing

Spot on David. I was initially told it needed calibrating etc...but after several resets and only after much guess work and some common sense...I figured it was some sort of speed sensor problem; especially as the only thing that is visibly wrong is the speedo behaviour.

On open highways when the speedo is mre stable, and when the unit depends on GPS alone, then I do not have a problem with it...i guess I will have to clean up the hall effect sensor and hope it fixes it...or buy a road map and take a step back into the 19th century.

thanks for the advice.
K

But Cerberas do not have Factory Fitted Sat Nav. And I have never heard of an aftermarket system being plumbed into the Speedo. So TokyoDEv, what sort of wierd and womderful SatNav do you have, and how is it wired into the Car.

Edited by jensena on Tuesday 5th December 12:43

[southendpier]

ha good point. silly question but can you not calibrate it to the right point in the settings menu?

i'm looking forward to the video - classic!

[Tokyokev]

jensena said:

Tokyokev said:

southendpier said:

jensena,

to explain, my factory fitted system in my daily jag uses GPS - but when a signal is not availbale - tunnels or tall buildings (ie Tokyo i guess) then it resorts to using the speed of the car to work out where it is until the "satellite" is found. (is it satellites or phone masts, cant remember?)

I guess this is the prob toykyokev is experiancing

Spot on David. I was initially told it needed calibrating etc...but after several resets and only after much guess work and some common sense...I figured it was some sort of speed sensor problem; especially as the only thing that is visibly wrong is the speedo behaviour.

On open highways when the speedo is mre stable, and when the unit depends on GPS alone, then I do not have a problem with it...i guess I will have to clean up the hall effect sensor and hope it fixes it...or buy a road map and take a step back into the 19th century.

thanks for the advice.
K

But Cerberas do not have Factory Fitted Sat Nav. And I have never heard of an aftermarket system being plumbed into the Speedo. So TokyoDEv, what sort of wierd and womderful SatNav do you have, and how is it wired into the Car.

Edited by jensena on Tuesday 5th December 12:43

I have absolutely no idea?

It's Sony. And that's about all the info I have...and the garage told me that it is wired mechanically to monitor speed? Again...no idea how. Will ask a few more questions...and try the calibration thing again...but it'S all in japanese...a bit had to figure out.

Best

K

PS: Weather permiting...the Route 246 run happens this weekend.

[jesfirth]

move to the uk

[david beer]

Most installed sat navs need a speedo pulse, you can in most cases dis-arm this "need" but then the accuracy is only as good as a portable. In the Griff i use a seperate hall effect IC sensing a magnet attatched to the driveshaft(£14). On the Rangie i disabled the speedo need. On the MX5 i use a system that detects tyre rotation after you have magnetised half the tyre, its pretty good but goes a little loopie at high speeds(£100ish).

[jensena]

david beer said:

Most installed sat navs need a speedo pulse, you can in most cases dis-arm this "need" but then the accuracy is only as good as a portable. In the Griff i use a seperate hall effect IC sensing a magnet attatched to the driveshaft(£14). On the Rangie i disabled the speedo need. On the MX5 i use a system that detects tyre rotation after you have magnetised half the tyre, its pretty good but goes a little loopie at high speeds(£100ish).

Bullshit :: Sat Nav is Sat Nav, A GPS recoiever picks up signals from at least 4 satellites, and calculates your position. It does not need a speed input to work out where it is, otherwise it wouldnt be Sat Nav. Sat Nav systems calculate your speed because it calculayes it has travelled from Position A to Position B in 'x' seconds, divide the distance by the time, and you have the speed. If it relied on a speed input then how can it calculate where you are?? In theory it'spossible if you travelled in a straight line, but how would it know if you have taken a left turn, or a right turnm, or even a U turn? It would only be guessing where you are, therefore it wouldnt be Sat Nav.

[mad mark]

Exactly what I was thinking!!
Whats the point of plugging them into the cars own speedo system?

[southendpier]

some do have sensors on the car particularly those that are factory fitted - the jaguar/navtech (i think)system I have works thus: when the gps signal is not available the satellite picture on the screen is blanked out and the car works out where it is by some measurment of physical /rolling movement. this is often inaccurate, but since it is generaly for a short period it doesn't matter, the system recalibrates when the sat signal is available. tokyokev is loosing his signal.

[jensena]

southendpier said:

some do have sensors on the car particularly those that are factory fitted - the jaguar/navtech (i think)system I have works thus: when the gps signal is not available the satellite picture on the screen is blanked out and the car works out where it is by some measurment of physical /rolling movement. this is often inaccurate, but since it is generaly for a short period it doesn't matter, the system recalibrates when the sat signal is available. tokyokev is loosing his signal.

In other words it's just guessing - a bit like a human being would when he doesnt kone where the hell he is Get a decent SatNac system.

[mad mark]

When entering a tunnel my TomTom will lose its signal, but will carry on giving you directions based on either (i've not worked out which yet) the speed you should be travelling, or the speed you were entering the tunnel at the time.

[Tokyokev]

I've decided it's going to be easier to move back to the UK.

[david beer]

I have fitted maybe 15 this year, including CD/DVD/Hard-drive and all need speedo pulse. Also repaired maybe 30. The hand held one i have does not need a pulse. So if yours does and the supplied one is not good, then you will get irratic movement. So for £14 from Farnell you can get a good one.

[southendpier]

jensena said:

southendpier said:

some do have sensors on the car particularly those that are factory fitted - the jaguar/navtech (i think)system I have works thus: when the gps signal is not available the satellite picture on the screen is blanked out and the car works out where it is by some measurment of physical /rolling movement. this is often inaccurate, but since it is generaly for a short period it doesn't matter, the system recalibrates when the sat signal is available. tokyokev is loosing his signal.

In other words it's just guessing - a bit like a human being would when he doesnt kone where the hell he is Get a decent SatNac system.

it is decent -! £2,500 of coventry's finest bits and bobs. I just need to sort out some more powerful satellites to fix on and i'll be as happy and a pig in dust...


..hang on, silly me - i've got the cerb now! I aint driving no jaguar - fool.

[jensena]

southendpier said:

jensena said:

southendpier said:

some do have sensors on the car particularly those that are factory fitted - the jaguar/navtech (i think)system I have works thus: when the gps signal is not available the satellite picture on the screen is blanked out and the car works out where it is by some measurment of physical /rolling movement. this is often inaccurate, but since it is generaly for a short period it doesn't matter, the system recalibrates when the sat signal is available. tokyokev is loosing his signal.

In other words it's just guessing - a bit like a human being would when he doesnt kone where the hell he is Get a decent SatNac system.

it is decent -! £2,500 of coventry's finest bits and bobs. I just need to sort out some more powerful satellites to fix on and i'll be as happy and a pig in dust...


..hang on, silly me - i've got the cerb now! I aint driving no jaguar - fool.

Get yourself a £200 Tom Tom then The satelites you use will be the same ones your £2500 one uses - the difference is, it will work..