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        General >> Give/Need advice to/from others >> speedo not working properly
        
(Message started by: andyw2000 on Sep 1^st, 2010, 7:29pm)

Title: speedo not working properly
Post by andyw2000 on Sep 1^st, 2010, 7:29pm

Hi,

I have a 95 TD manual Ghia and the speedo is playing up, it reads between 10 and 20 miles under what I am really doing. I have had a look on the web site and forum but can't seem to find anything about problems with speedo's on there.
Do I need to get some new clocks or is there a sensor or something that needs replacement.
Any help would be appreciated.

Thanks
Andy :)

Title: Re: speedo not working properly
Post by Highlander on Sep 1^st, 2010, 9:09pm

Hi Andy,

has it just started doing it? is it a new car to you?

is the speedo erratic, jumping up and down on does it run as normal but just show the slower speed?

Normally the Scorpio speedos read above the actual speed so there is definitely a problem somewhere.

i'd guess first of all at the Vehicle Speed Sensor (VSS) or the wiring for it.

Possibly you have had a different ratio differential fitted?

Title: Re: speedo not working properly
Post by andyw2000 on Sep 2^nd, 2010, 3:37pm

Thanks, I will have a look at the connections to the speed sensor, do you know where it is located?.
I got the car about 2 months ago and it was like it then, the speedo seems to start late but works as it should and slowly increases in speed in a smooth action but just 10-20 MPH slower than I am really doing.
I don't think the diff has been changed, it has had 2 owners who lived next door to each other and now just gone over 100k and doesn't look as its been changed.

Regards
Andy

Title: Re: speedo not working properly
Post by Highlander on Sep 2^nd, 2010, 4:04pm

NS of the gearbox.

this is an autobox but the sensor looks very similar to the manual one.

http://i41.tinypic.com/qxksc3.jpg

Title: Re: speedo not working properly
Post by Tompion on Sep 2^nd, 2010, 8:34pm

Have you ever done an instrument reset or had the needles flick round? If not it might be worth a try. With the ignition on press and hold the odometer reset button until it goes into diagnostic mode. Next time you turn on the ignition the needles will flick & reset.

See here:
http://www.fordscorpio.co.uk/instreset.htm

Title: Re: speedo not working properly
Post by Highlander on Sep 2^nd, 2010, 8:46pm

When you're doing the reset take a look at reading 1 (Type of Instrument cluster)

you may possibly have had a replacement cluster of the wrong type which may affect the speedo , it can affect the rev counter if the wrong one if fitted however i'm not sure about the speedo..

Title: Re: speedo not working properly
Post by Mike H on Sep 4^th, 2010, 12:25pm

Silly question time ;D ~ how do you know what speed you are "really doing" ?

Title: Re: speedo not working properly
Post by tonyboy on Sep 4^th, 2010, 2:52pm

If you drive with a sat nav my reading is about 10% above the sat nav

Title: Re: speedo not working properly
Post by andyw2000 on Sep 4^th, 2010, 4:49pm

Hi,
Just gave that a try but it hasn't made any difference, it must be the speed sensor playing up, I will have a look at it tomorrow, I think I have a speed sensor that I took off a BOA cossie auto box but I bet its different.

Thanks for the reply and advise

Regards
Andy

on 09/02/10 at 20:34:12, Tompion wrote:

:) :)

Title: Re: speedo not working properly
Post by andyw2000 on Sep 4^th, 2010, 4:55pm

Hi,
Well I had the wife behind me when I picked the car up and she was clocking 65 and mine was only showing 50 and when I just went out after the reset I had the sat nav on which is exactly the same speed when its in my work van and that was showing 50 and the speedo was showing about 35.
It did seem slightly better if I did the reset then just drove rather than turning the ignition off and on again but it maybe my imagination!!!

on 09/04/10 at 12:25:23, Mike H wrote:

Silly question time ;D ~ how do you know what speed you are "really doing" ?

:) :) :)

Title: Re: speedo not working properly
Post by andyw2000 on Sep 4^th, 2010, 4:56pm

Thanks for the pic I will have a look tomorrow.

on 09/02/10 at 16:04:09, Highlander wrote:

NS of the gearbox.

this is an autobox but the sensor looks very similar to the manual one.

http://i41.tinypic.com/qxksc3.jpg

Title: Re: speedo not working properly
Post by Mike H on Sep 5^th, 2010, 2:41pm

on 09/04/10 at 14:52:11, tonyboy wrote:

If you drive with a sat nav my reading is about 10% above the sat nav

Ah, cunning. ;D

Has it got non-standard larger wheels? Or new tyres?

Title: Re: speedo not working properly
Post by andyw2000 on Sep 5^th, 2010, 4:55pm

Hi,
I had a look at the sensor today and gave it a clean but it hasn't made any difference.
What I did discover though that when I did the reset I then pushed the button again and got some other info up and one of them said speed and when I drove the car in this mode it was showing 35mph on the display but the needle was only showing 25.
Would anybody know if the speed sensor on the gearbox give the reading for both of these?, if it does then I would think that the speedo head is the problem unless somebody has previously taken the speedo to bits and the needle has been put back on but not in the right place and that why it seems to start reading at about 10mpg if that is possible??.

The wheels are the originals and the tyres are standard size and have about 80% tread left.
:)

Title: Re: speedo not working properly
Post by Tompion on Sep 5^th, 2010, 7:10pm

It says on the instrument reset page:
"Vehicle speed sensor. Shows the actual speed of the vehicle in KPH. This should be within +5% of the MPH"

Assuming that's correct & it is KPH it's probably about right.