Speed sensor stop functioning

Guys, Guys This is a 2 min. check.

First make a continuity check of the wires going to the sender at the plug.

If no continuity, stick straight pins in the wires at the sender as close as you can and check for continuity again.

If you have continuity at the pins than the wire is bad.

If you have continuity all the way to the plug then the sender is ok but the wheel is not spinning.

If you have the sender out you can spin it and you should read pulses at all is well at the connector.

This is best checked with an analog meter because sometimes digital meters will not read pulses.

Thank you all for your tips.

I did try do remove the paddle wheel steel axis in order to remove it from the plastic housing, to clean and and check the wire, but no way. Using a small screw driver and forcing the axis on one of the sides, did not work. The manual refers a specific wheel position (a more flat paddle way down), but apparently all the four paddles are equal!

The manual also refers to a special tool to remove more easly the axis, delivered with a ... new sensor+cable (200 + Euros)

So, I will try to follow Roline and Timebandit suggestions.

Thank you all,

Alf,

Alf, there is usually a small bit of iron or a small powerful magnet in one or two of the paddles. You can find out which paddle is "special" by using any conventional magnet, it will attract to that one (or two) special paddle blades. Unless that special bithas fallen out of the blade, in which case you'd see the hole it left, there's not much to be done with the paddle itself. If you can hold it up to your mouth and spin it by blowing on it--it works.
If it doesn't spin, soak it in some Limeaway or CLR or other lime remover and then try a drop of thin oil to lubricate the pin.

What usually happens is that the pickup coil, a coil of wire or a solid-state sensor that is in the housing usually right "above" the paddlewheel, has gotten waterlogged and failed. In this case, all you can do is change the whole impeller/sensor assembly.

SOMETIMES you get lucky, and the problem is that the wire going into the sensor has been crimped, stepped on, or damaged. In that case, you have someone blow on the paddle wheel to simulate it working, while someone else wiggles the wire where it leaves the sensor. Either nothing will show on the display--or the display will suddenly start working. In which case, you can cut and splice in a new wire of similar type. Similarly, if the cable has been damaged ANYWHERE between the display and the impeller--that's all it takes to knock out the whole thing. Crushed? Nicked? Chafed where it runs through a bulkhead?

But in order to confirm that it is the paddle wheel versus the display unit, the best way is still to use an old-fashioned voltmeter with a needle on it. It should show some small voltage and amperage when the impeller is being spun, offhand that could be as little as 1/2 volt at 50 milliamps, AC. It isn't much. You might try to get more specific numbers from the maker.