V40 Speedometer Inaccurate

[mikealder]

Originally Posted by Clan

Remember a GPS device only shows correect speed in a straight line and on a level surface ...

The calculations you can do are rather involved, but trust me unless you are driving an F1 car up a gradiant of one in three or constantly changing heading by a large degree at high speed the GPS will be far more accurate than anything fitted to a car by the manufacturer when driving normally on the road.

The only time time a GPS speed will differ in a car on a public road is during very heavy acceleration or braking as it only updates once per second unless you have a more exotic receiver that supports 20Hz reception which is good for the race track - Mike

[grass hopper]

Originally Posted by Dog_Book

My 1998 is all electronic

yes,i think jasonD is electronic also.

[Baffler]

As stated - analogue clock will work off a cable - digital clock will take signal from sensors.

i am sure the abs wheel sensor provides the pulse for the speedometer

It could be a build up of crud over the ABS sensors causing a poor signal (the ABS sensors are very difficult to remove without breaking!). Also check there is no crud in the castellated rings on the front hubs.

[sebaveh]

What about odometer? Does it show mileage correct?

[grass hopper]

Originally Posted by Baffler

As stated - analogue clock will work off a cable - digital clock will take signal from sensors.



It could be a build up of crud over the ABS sensors causing a poor signal (the ABS sensors are very difficult to remove without breaking!). Also check there is no crud in the castellated rings on the front hubs.

the abs module/speedo gets a reading of all 4 sensors.

if one sensor is reading incorrect it would put the abs warning light on,cant see all 4 reading incorrect.