Speedo needs to “warm up”

[del mar]

Evening,

R129 merc sl.

This is a good one.

The needle on the speedo need 5 mins to warm up before it starts to work.

The first couple it doesn’t move, then it starts to bounce around a bit up to 20mph, eventually it starts to work.

Car is 25 years old, lots of dodgy electrics on it now.

What would cause this ?

Thanks

Del

[GreenV8S]

Don't know what type of sensor that uses, but perhaps it's some combination of an air gap slightly too big and/or an MVR sensor that isn't as magnetic as it used to be or something along those lines. Could conceivably even be an electronic failure which is healing when something gets hot.

[PositronicRay]

Cleaning fuses and re-seating connectors with a little contact cleaner works wonders. Try the connectors on the cluster.


If you weren't getting a speed signal your roof and cruise would be inop, are they okay?

[stevieturbo]

Test the output from the sensor. Simplez. That will direct you closer to the source of the problem.