Ford Scorpio Speedo problem

*doh*, the stereo has speed dependant volume control- gets louder as u speed up. The pickup on back of gearbox, or wiring has a dodgy connection causing your wonky speedo- and radio volume changing. Check it out.

Tim..

The message from "Still_21" contains these words:

It's a feature. The radio volume is intended to increase as the speed increases to save you having to twiddle it all the time. Your speedo feed is dying and this is telling the radio you're going slower so it's cutting the volume accordingly.

I've no idea how your speedo works though!

Me too, but most cars I've come across have a cable running from the gear box to the back of the instrument panel. The wire inside this cable is turned by a cog in the gearbox. At the other end of the cable the wire spins a disc behind the speedometer which induces the movement of the needle that you see. Sometimes the speedo cable gets squashed between other inhabitants of the engine bay which could cause the problem. Usually before they break a couple of strands of the cable stay in place long enough to move the needle. A third possibility is that one end of the cable has simply come loose and can be pushed back into place.

If you intend to replace the cable yourself follow the instructions in the Haynes manual but connect it to the speedo before connecting to the gearbox. Space behind the speedo is usually limited so any extra cable length there is useful.

dp (no@mail) gurgled happily, sounding much like they were saying :

Not recent cars, and *especially* not with things like speed-sensitive stereos.

As has been said, there's a speed sensor on the 'box, which is dying or the wiring from it's shagged.

Many thks to those who replied, least you've put my mind a rest, thought it may be serious mucking up the radio. The sensor is around £57 from fords but they said a bitch to fit as you have take off the gearbox 'arm'

I'd say this is rather unusual on anything other than a cheap low spec car these days. Most are elecronic with no mechanical link to the gearbox. You need some form of electronic speed sensor for the ABS etc, so it makes no sense to double up.

And my 20 year old Rover SD1 has an electronic speedometer.

it's a cable not electric as it was on the pre 92 cars the cable is either on it's way out or the gearbox end of the drive is wearing out end of live with it if you can't solve the problem but don't pay for the speed sender unit pick one up from another ford and cut it to length (the metal bit inside) they will be virtually free from the scrappy

They went back to a cable? Wonder why? With ABS, you already have a speed sensor...

The message from Dave Plowman contains these words:

Bloodymindedness?

don't know but the speed sensor in the abs isn't hooked up to anything else in fact, the wires are suppresed to stop any interferance fomr any other signals in 3 different rates depending on which vehicle they were fitted to (the higher the spec, the more the suppresion obviously because there was more electrical equipment fitted)

the speed sensor that all the ford vehicles use is just a normal speed sensor (as in a bit of magnet thing on a stick) and you just cut the stick to fit whatever you need it to fit to

Main dealers seem to find each and every part a bitch to fit. My guess is that the gearbox 'arm' is the linkage to the gearlever. This is just nuts and bolts and rods and joints, unless there is some new fangled electric version of this too ;)

I expect the speed sensors for the ABS are separate as ABS is a safety critical system and the speedometer isn't, so it makes sense to have some redundancy. The ABS ones are probably more dependable (lower failure rate) or at least you would hope so!

You'd need to tell BMW of your fears, then. ;-)

Tom Robinson ( snipped-for-privacy@alkali.spamfree.org) gurgled happily, sounding much like they were saying :

Umm, I've had several ABS sensors fail but never a gearbox speed sensor. It's down to the ABS sensors living in a hostile environment, in all the road filth, with the wires exposed to regular flexing (in two planes for the front), whereas the gearbox one just has a little bit of warmth and vibration.

The reason that the two are separate is probably down to the fact that not all cars in a model range will have ABS, so why develop, produce, stock two separate speedo heads working from two separate sensing mechanisms? Cost, y'see...

I'm afraid gearbox sensor failure is all too common - they get very hot, especially in autos.

Dave Plowman (News) ( snipped-for-privacy@davenoise.co.uk) gurgled happily, sounding much like they were saying :

Hmmm. I've obviously been lucky, so far.

Shit. Y'know what this means, don't you?

Next sodding week...

The message from Adrian contains these words:

If this ain't a silly question - why aren't ABS sensors inboard on the driveshafts up by the diff instead of stuck out there in all that muck?

Guy King ( snipped-for-privacy@zetnet.co.uk) gurgled happily, sounding much like they were saying :

On the driven end, .

On the non-drive end, though, it's fairly obvious.

The message from Adrian contains these words:

Well, yes, it'd be a strange idea to have a quill shaft from the undriven wheels to a central box. Perhaps the French will do it sometime.