940 speedo not working

[offtheclockuk]

as per title, an old mate of mine has a '92' 940 2.0 petrol,

thing is see... in the dry, the speedo dont work, but find yerself a puddle an hey presto all on and cookin wi gas,

is the early abs stuff like the old merc setup where the speed sensor for the speedo is on the rear diff?

if so does any one know of any points along the loom where the wiring may suffer corrosion, just a heads up before i get chance to take a look at it.

ta james

[smithy]

yes the speedo sencer is on the back plate of the diff mate

[offtheclockuk]

cheers for the reply smithy.

so maybe rotten wiring mate?

you wouldnt know which side of the car the wiring would run, and where it enters the car?

ta james

[smithy]

cheers for the reply smithy.

so maybe rotten wiring mate?

you wouldnt know which side of the car the wiring would run, and where it enters the car?

ta james

if it works when it gets wet then check the sencer on backplate of diff ,its proberly the conecter to the sencer has rotten away

[rogerhechorister]

It's usually the wire right by the diff above teh back axle.

[DaveC19]

If its not the sensor or the wiring then the electronics behind the dash has gone wonky.

I had this problem in my '92 940 est. I would put in the key and turn on the ignition but then I was doing 35 mph before I started the engine :-(
Not worth trying to fix the electronics - just replace the entire dash unit (5 gauges & warning lights) with a replacement from a breaker.

Mine cost €100 - €50 for the part & €50 for the labour (my garage specialise in high end cars, volvo/merc/bmw etc., so they know what they are doing and as I've been dealing with them for 30 yrs I trust them - this cannot be said of all garages - know what I mean ;-) ).

I lost 20K in mileage as the replacement had 20K more than my own odometer but thats a minor irritation.

Oh for the days when the speedo was driven by a cable from the box !!! Life was much simpler then :-)

This is probably out of date now but may help someone else :-)